Exam 1 Flashcards

Question

Deep

Answer 1

Further from the surface of the body

Answer 2

* A plane that passes directly through the midline of the body * Divides the mass of the body in half * 3 cardinal planes: * Sagittal - right/left halves * Frontal - anterior/posterior * Transverse/Horizontal - superior/inferior

Answer 3

Involves flexion, extention, abduction and adduction

Answer 4

* Imaginary line positioned perpendicular to a plane * All movement occurs around an axis * Axis is at the center of mass for whole body movements * imaginary line about which a joint or structure revolves * Axis is usually a joint for segmental movements

Answer 5

Directed vertically Rotational movements in the **transverse** plane occur

Answer 6

Directed along the sagittal plane Rotations in the **frontal** plane occur

Answer 7

Directed along the frontal plane Rotations in the **sagittal** plane occur

Answer 8

* Motion along one axis in which all points of the system move at the same time, in the same direction, with respect to the defined reference frame * Path may be represented by one point traveling along a line from one place to the other * Also called *Linear* motion

Answer 9

* Path of a system can be straight or curved * Rectilinear translation: path of the system is a straight line * Curvilinear translation: path of the system is a curved line

Answer 10

* Occurs when the system is restricted to move around a fixed axis - therefore in a circular path * Also called angular motion

Answer 11

* Combination of tranlation and rotation * most human motion is general

Answer 12

* A skill performed under standard environment conditions * e.g. basketball free throw * Goal is always the same height * Free throw line is the same distance from the goal * Ball is standard size and weight

Answer 13

* A skill that must be altered because of the changing dynamics of the activity, environment, or object of interest * e.g. passing and dribbling during a soccer game * During a game, no two passes are identical * Dribbling is a dynamic skill that changes contantly depending on defensive pressure, open spaces, position of teammates and velocity of player with the ball

Answer 14

* Change in position with respect to spatial and temporal frames of reference * No motion occurs without force

Answer 15

* Movement with a definite beginning and end-point * e.g. broad jump

Answer 16

* Cycles of motion performed repeatedly with no well-defined beginning or end-points * e.g. walking

Answer 17

* Movements that appear to be continuous but are really a combination of discrete motions * e.g. rowing

Answer 18

* System of linked rigid bodies subject for force application * Simple kinetic chain: each segment participates in no more than two linkages * e.g. arm * Complex kinetic chain: a segment is linked to more than two other segments * e.g. torso

Answer 19

* Open kinetic chain * the most distal segment is free to move * e.g. barbell curl * Closed kinetic chain * the most distal segment is stationary * e.g. push up * Total chain has less mobility than open kinetic chain

Answer 20

* Strength or energy as an attribute of physical action or movement * A push or a pull * Characterized by magnitude, direction, and point of application

Answer 21

* External/Internal * Contact/Non Contact * Action/Reaction * Motive/Resistive

Answer 22

Newtons (N)

Answer 23

* 1 N = 0.225 lbs. of force or * 1 lb. of force = 4.448N

Answer 24

* Act within the defined system * Internal forces can change only the shape of the system

Answer 25

* Forces that act on an object as a result of its interaction with the environment surrounding it * Only external forces can cause a change in the motion of a system

Answer 26

Pulling forces which act on the ends of the internal structure

Answer 27

* Pushing forces that act on the ends of an internal structure * Internal forces hold things together when the structure is under tension or compression

Answer 28

* Forces that occur without contact * Gravity * Magnetic forces * Electrical forces

Answer 29

* Gravity * 9.81 m/s²

Answer 30

* The amount of gravitational force exerted on a body * W = mg (product of mass and the acceleration of gravity)

Answer 31

* Quantity of matter composing a body (dog, tree, desk, swimming pool, you) * Represented by m * Units are in kg

Answer 32

The result of physical contact between two bodies

Answer 33

* The initially applied force

Answer 34

* The "opposite force" * The simultaneous equal counterforce acting in the opposite direction to the action force

Answer 35

* Increases the speed of an object * Changes direction of an object * Usually concentric

Answer 36

* Resists motion * Decreases speed * Usually eccentric

Answer 37

* Direction: **way** the force is applied * Magnitude: **size** of the applied force * Point of application: point at which the system **receives** the applied force * Line of action: imaginary line extending indefinitely along the **vector** through the tip and tail

Answer 38

* The single resultant force derived from the vector composition of all the acting forces * The force that determines the net effect of all acting forces on a body

Answer 39

* Force per unit of area over which the force acts * Commonly used to describe force distribution within a fluid (blood pressure, water pressure) * P = F/A * Measured in N/cm² & in Pascals (Pa)

Answer 40

* Distribution of force within a body, quantified as force divided by the force over which the force acts * Commonly used to describe force distribution within a solid * Measured in N/cm²

Answer 41

* Force acting over an area of contact between two surfaces in the direction opposite that of motion or motion tendency * Quantified in units of force (N) because friction is a force * Starting friction is greater than moving friction * It takes more force to start moving an object than it does to keep it moving

Answer 42

* (F_m) * As magnitude of applied force becomes greater and greater, magnitude of opposing friction force increase to a critical point

Answer 43

Magnitude of friction

Answer 44

* Static bodies: friction is equal to the applied force * Dynamic bodies: friction is constant and less than maximum static friction

Answer 45

Force quantities described by **magnitude** and **direction**

Answer 46

Quantities that have **magnitude** but **no specific direction**

Answer 47

Mass, volume, length, and speed

Answer 48

* The composition of vectors with the same direction requires adding their magnitudes * Forces that have the same line of action * The forces may act in the same direction or opposite direction on the same line

Answer 49

Process of determining a single vector from two or more vectors by vector addition

Answer 50

* Segments are represented with lines connecting points * Forces are represented by vectors or arrows

Answer 51

* Two vectors are considered equal if they possess the same magnitude and direction A = B

Answer 52

The composition of vectors with the opposite directions requires subtracting their magnitudes

Answer 53

A vector that represents the sum of all forces (net force) acting upon a system

Answer 54

Operation that replaces a single vector with two perpendicular vectors such that the vector composition of the two perpendicular vectors yields the original vector

Answer 55

* Do not act along the same line * All forces pass through a common point

Answer 56

* A²+ B² = C² * sin = O/H * cos = A/H * tan = O/A

Answer 57

Form or technique

Answer 58

* Change in location * The directed distance from initial to final location * The vector equivalent of linear distance * Measured in units of cm, m, km * Vector quantity: initial to the final position

Answer 59

* The total length of the path traveled by the system of interest * Scalar in nature; only tells magnitude

Answer 60

* Distance covered over the time taken * Speed = Distance/Time * A scalar quantity * Measured in units of m/s

Answer 61

Stride Length & Stride Frequency

Answer 62

* Standardizing descriptions of human motion * Most commonly used is the Cartesian coordinate system * Human body joint centers are labeled with numerical x and y coordinates for 2D * x, y, and z for 3D

Answer 63

* Defined as location in space * Where is an object in space: * At the beginning of it's movement? * End of the movement? * Some time during its movement?

Answer 64

* The rate of change in location * Velocity = Displacement/Time * The vector equivalent of linear speed * Measured in units of m/s

Answer 65

* Speed = rate of motion * Rate of distance traveled * Velocity = rate of motion in a specific direction * Rate of displacement * Displacement = vector quantity = so is velocity

Answer 66

* Same **rate of motion** * Periods of speeding up and slowing down

Answer 67

Maximum rate of motion achieved

Answer 68

* Average: Velocity or speed over whole time interval * Instantaneous: Rate of motion at one given instant in time

Answer 69

* Change in velocity divided by the time it took for the change in velocity to take place * The rate of change in linear velocity * Acceleration = change in velocity/time * a = V₂ - V₁ / t * Measured in units of m/s² * Can be 0, negative or positive

Answer 70

A body in free fall that is subject only to the forces of gravity and air resistance

Answer 71

The vertical component is influenced by gravity and the horizontal component is not

Answer 72

* Two balls - one dropped and one projected horizontally from the height * Both land at the same time since gravity affects their vertical velocities equally

Answer 73

The force of gravity produces a constant acceleration of **-9.81m/s²** on bodies near the surface of the earth

Answer 74

Symmetrical about the apex

Answer 75

Vertical velocity **decreases** as the ball **rises** and **increases** as the ball falls due to the influence of gravitational force

Answer 76

1. The angle of projection 2. The projection speed 3. The relative height of projection

Answer 77

The direction of projection with respect to the horizontal

Answer 78

The magnitude of projection velocity

Answer 79

* Incorporates both the intial speed (magnitude) and the angle of projection (direction) into a single quantity * When initial velocity is resolved the horizontal and vertical components will have separate speeds

Answer 80

The difference between projection height and landing height

Answer 81

A body will maintain a state of rest or constant velocity unless acted on by an external force that changes its state

Answer 82

* Product of an object's mass and its linear velocity * Linear momentum = M * M = mv * Units: (kg)(m/s)

Answer 83

When two objects collide head-on, their combined momentum is **conserved**

Answer 84

* Objects in collision stay together and move together with the same velocity * Also called plastic collision * Most collisions are not perfectly inelastic or elastic, they are usually somewhere in between

Answer 85

When two bodies undergo a direct collision the difference in their velocities immediately after impact is proportional to the difference in their velocities immediately before impact

Answer 86

1. Velocities 2. Temperature 3. Material 4. Spin

Answer 87

* Assuming mass remains constant, the greater the force, the greater the acceleration * Acceleration is inversely proportional to mass

Answer 88

* The combination of forces produced by different parts of the human body * When a person is moving or attempting to move an object, several different parts of the body act together to maximize the force * Sequential and simultaneous force

Answer 89

* A force (F) applied to a body causes an acceleration (a) of that body of a magnitude proportional to the force, in the direction of the force, and inversely proportional to the body's mass (m) * F = ma

Answer 90

Product of force and time interval the force acts

Answer 91

* For every action, there is an equal and opposite reaction * F₁ = F₂

Answer 92

* Product of force and the amount of displacement in the direction of that force * Means by which energy is transferred from one object or system to another * U = F(d) * Units = J = 1 J = 1 Nm

Answer 93

* Capacity to do work * Biomechanics = concerned with mechanical energy * Mechanical energy comes in 2 forms * Kinetic * Potential

Answer 94

* Moving object has the capacity to do work due to its **motion** * Affected by the mass and the velocity of the object

Answer 95

The energy that an object has due to its **position**

Answer 96

Gravitational potential energy Strain energy

Answer 97

* Potential energy due to an objects position relative to the earth * GPE of an object is related to the object's weight and its elevation or height above the ground or some reference * PE = Wh

Answer 98

Energy due to the deformation of an object

Answer 99

* Rate of work production * Can be thought of as how quickly or slowly work is done * P = U/T * Measured in Watts * 1W = 1 J/s

Answer 100

* Compression and tension are axial stresses * Shear stress is a transverse stress that acts parallel * Shear Stress = F/A

Answer 101

* Asymmetric loading that produces tension on one side of a body's longitudinal axis and compression on the other side * Multiple stresses along the analysis plane

Answer 102

* The rotary effect of a force * The angular equivalent of force * AKA as moment of force

Answer 103

Load producing twisting of a body around its longitudinal axis

Answer 104

* Repeated application of a subacute load that is usually of relatively low magnitude * Microtrauma

Answer 105

* Application of a single force of sufficient magnitude to cause injury to a biological tissue * Macrotrauma

Answer 106

Quantification of the deformation of a material

Answer 107

1. Linear strain 2. Shear strain

Answer 108

Occurs as a result of a change in the objects length

Answer 109

Occurs with a change in orientation of adjacent molecules as a result of these molecules slipping past each other

Answer 110

* When an object is stretched, it becomes narrower; if the object is compressed, it becomes wider in the lateral direction * Ratio between strain in the axial direction to strain in the transverse direction * Most materials = between 0.25 and 0.35 * Example: intervertebral discs

Answer 111

Decrease their height by an average of 2cm throughout the day, with approximately 54% of the loss occuring in the first 30 minutes

Answer 112

Stress/strain in a loaded material; stress divided by the relative amount of change in shape

Answer 113

* Change in shape * Force applied on object = acceleration and deformation

Answer 114

An object facing a load will reach a yield point at which deformation occurs until the ultimate failure point is reached, in which permanent damage is done

Answer 115

Bone is anisotropic, it has different srength and stiffness depending on the direction of the load

Answer 116

* Cortical bone = higher mineral content = stiffer = withstand greater stress * Trabecular bone = less compact minerals = more porous = withstand more strain

Answer 117

Calcium carbonate and calcium phosphate make contribute to 60-70% of bone stiffness and strength

Answer 118

* LIke muscle, bones respond to certain kinds of training through hypertrophy

Answer 119

The densities and to a lesser extent, the sizes and shapes of bones are determined by the magnitude and direction of the acting forces

Answer 120

* Osteoblasts and osteoclasts are continually building and resorbing bone, respectively. * Increased or decreased mechanical stress leads to a predominance of osteoblast or osteoclast activity, respectively.

Answer 121

* Spreads load over wide area, reducing contact stress * Provides a protective lubrication that minimizes friction and mechanical wear at the joint * AKA hyaline cartilage * 10-30% collagen

Answer 122

* Soft, porous and permeable material * Consists of chondrocytes * Under load = exudes synovial fluid = creep

Answer 123

Maintain and restore cartilage from wear

Answer 124

Soft-tissue discs or menisci that intervene between articulating bones, as exemplified by the menisci of the knee

Answer 125

* **Distributing loads** over joint surfaces * **Improving the fit** of articulations * **Limiting slip** between articulating bones * **Protecting** the joint periphery * **Lubricating** the joint * **Absorbing shock** at the joint

Answer 126

* Similar in composition and structure * By weight, tendons and ligaments consist of approximately: * 70% water * 25% collagen * 5% ground substance and elastin * Ligaments have more elastin than tendons

Answer 127

* Attach muscles to bone * Consist of groups of collagen fibers, which are bound together in parallel * Parallel arrangement produces a material very stiff and high in tensile strength * Parallel arrangement has little resistance to compession or shear forces

Answer 128

* Fibrous CT which attaches bone to bone and serves to hold structures together and keep them stable * Different arrangement than collagen fibers and a slightly larger elastin component than tendons - making them less stiff and slightly weaker than tendons * Non parallel collagen alignment = withstand uniaxial loads

Answer 129

* Unlike connective tissue, muscle tissue is capable of actively contracting to produce tension within itself and the structures to which it attaches * The active contractile components of muscle thus determine the stiffness of the muscle at any instant * Muscle stiffness varies as a function of the number of active contractile elements

Answer 130

* The force of muscle action varies from slight to maximal in one of two mechanisms: * Increasing the number of motor units recruited * Increasing the frequency of motor unit discharge

Answer 131

* Provide mechano-sensory information about changes in muscle fiber length and tension * Primarily respond to muscle stretch through reflex action by initiating a stronger muscle action to counteract the stretch * More spindles exist in muscles that routinely perform complex movements

Answer 132

* The stretch reflex consists of three main components: * Muscle spindle that responds to stretch * Affarent nerve fiber that carries the sensory impulse from the spindle to the spinal cord * Efferent spinal cord motor neruon that activates the stretched muscle fibers

Answer 133

* Connect in series to skeletal muscle fibers and also located in ligaments of joints to primarily detect differences in muscle tension * When activated by excessive muscle tension or stretch, GTOs immediately transmit signals to cause reflex inhibition of the muscles they supply * Protect muscles and its CT fom injury by sudden, excessive load or stretch

Answer 134

* Body weight * Tension in the spinal ligaments * Tension in the surrounding muscles * Intraabdominal pressure

Answer 135

* Resulting from: * Body weight + weight held by arms and hands

Answer 136

* Total body center of gravity is anterior to the spinal column * Spine is placed under constant forward bending movement

Answer 137

* Flexion * Extension * Hyperextension * Lateral Flexion * Rotation

Answer 138

* Vertebral column * Motion segment * Vertebrae * Intervertebral Discs * Annulus fibrosus * Nucleus pulposus

Answer 139

* AKA functional spinal unit (FSU) * Smallest physiological motion unit of the spine to exhibit biomechanical characteristics similar to those of the entire spine * A motion segment consists of two adjacent vertebrae, the intervertebral disc and all adjoining ligaments between them

Answer 140

* Annulus fibrosus consists of 90 concentric bands of collagenous tissue * Collagen fibers crisscross vertically at a 30° angle to make the structure able to withstand rotational strain

Answer 141

* Influenced by heredity, pathological conditions, individual's mental state, and forces to which the spine is habitually subjected * Prestress * Primary spinal curve * Secondary spinal curve * Lordosis * Kyphosis * Scoliosis

Answer 142

* The ligamentum flavum is in tension even when the spine is in anatomical position, enhancing spinal stability * The tension = constant compression in in the intervertebral discs, referred to as prestress

Answer 143

Present at birth = c-shape for babies

Answer 144

Begin to develop when children start to sit up and stand

Answer 145

* Refers to the normal inward curvature of the limbar and cervical regions of the spine * Cause = Congenital spinal deformity, weakness of the abdominal muscles, poor postural habits

Answer 146

* Also called roundback, a condition of over curvature of the thoracic vertebrae * Cause = degenerative diseases, developmental problems (Scheuermann's disease) osteoporosis with copression fractures of the vertebrae, or trauma

Answer 147

* Vertebrae grow unevenly * One or more wedge shaped vertebrae develop because of abnormal epiphyseal plate behavior

Answer 148

* Condition in which a person's spine is curved laterally * Classified as either congenital, carrying heavy objects, leg length discrepancies and unknown

Answer 149

Back muscles, with a moment arm of approximately 6cm, must counter the torque produced by the weights of the body plus any external loads

Answer 150

* Most common type of vertebral fracture is in pars interarticularis * Spondylolysis * Spondylolisthesis * Spondylolysis and spondylolisthesis dont tend to heal with time * Common with sports involving repeated hyperextension of the limbar spine

Answer 151

* Synarthroses * Syndesmoses * Amphiarthroses * Synchondroses * Symphyses * Diarthroses or synovial

Answer 152

Where fibrous tissue binds bones together

Answer 153

* Coracoacromial * Mid-tibiofibular * Inferior tibiofibular

Answer 154

They are slighly moveable

Answer 155

The articulating bones are jointed by a thin layer of hyaline cartilage

Answer 156

Epiphyseal plate before ossification

Answer 157

Vertebral joints

Answer 158

* Articular cartilage * Articular capsule * Synovial membrane * Synovial fluid * Associated bursae

Answer 159

A double layered membrane that surrounds the joint (ligamentous sleeve)

Answer 160

Membrane that lines the interior of the articular capsule

Answer 161

A clear, slightly yellow liquid that provides lubrication inside the articular capsule

Answer 162

Small capsules filled with synovial fluid that cushion the structures they separate

Answer 163

* 160 in the body * Decreases friction between two joints

Answer 164

Loses its gliding capabilities and becomes irritated during movement

Answer 165

* Gliding * Hinge * Pivot * Condyloid * Saddle * Ball & socket

Answer 166

* Articulating bone surfaces are nearly flat * Movement = nonaxial gliding * Examples: * Intermetatarsal * Intercarpal * Intertarsal * Facet joints

Answer 167

* One articulating bone surface in convex and the other is concave * Strong collateral ligaments restrict movement in a planar hinge-like motion * Examples: * Ulnahumoral * Interphalangeal * Tibiafemoral joints

Answer 168

* Rotation is permitted around one axis * Examples: * Atlantoaxial joint and the radioulnar joint

Answer 169

* One articulating bone surface is an ovular convex shape, and the other is a reciprocally shaped concave surface * Movement: Flexion, extension, abduction, adduction and circumduction * Examples: * 2nd-5th metacarpalpholangeal joints and the radiocarpal joints * Radiocarpal joints

Answer 170

* Both sides shaped like a riding saddle * Movement: Same as the condyloid joint * Example: * Carpometacarpal joint of the thumb

Answer 171

* Surfaces of the articulating bones are reciprocally convex and concave * Movement: Same as condyloid, but greater range of motion * Movement in all 3 plans of motion are permitted * Examples: * Hip joint * Shoulder joint

Answer 172

* Refers to the joint's resistance to movement of planes other than those defined y the degrees of freedom of movement for the joint * Ligaments and tendons help resist tensile forces acting at the joints

Answer 173

* Articulating bones have their maximum area of contact with each other * Position that joint stability is greates

Answer 174

Full extension

Answer 175

Position in which the area of contact and joint stability is reduced

Answer 176

A description of the relative ranges of motion allowed at a joint in different directions from anatomical position (0 degrees)

Answer 177

The angle through which a joint moves from anatomical posiiton to the extreme limit of segment motion in a particular direction

Answer 178

* Intervening bony or muscle tissue or fat at the end of the ROM * Tightness/laxity in the muscle and collagenous tissue crossing a joint * Muscle fatigue

Answer 179

* **Golgi tendon organs:** inhibit tension in muscle and initiates tension development in antagonists * **Muscle spindles:** provoke reflex contraction in stretched muscle & inhibit tension in antagonists

Answer 180

* **Proprioceptive neuromuscular facilitation** is a group of stretching procedures involving alternating contraction and relaxation of the muscles being stretched

Answer 181

Goal: Enhance both active and passive range of motion 1. An active PNF stretch involves a shortening contraction of the opposing muscle to place the target muscle on stretch 2. The passive stretch is then followed by an isometic contraction of the target muscle 3. This is repeated 3-4 times with the assistance of a partner

Answer 182

* Contractility - produce force * Irritability - ability to be stimulated * Extensibility - ability to be stretched * Elasticity - ability to return to original shape if deformed (stretched)

Answer 183

* **Paralell elastic component** - passive elasticity derived from muscle membranes * **Series elastic component** - passive elasticity derived from tendons when a tensed muscle is stretched

Answer 184

* Cardiovascular function * Motivation * Training size * Muscle size * *fiber type is not a sole predictor of success*

Answer 185

* **Active Insufficiency:** Failure to produce force when slack * *Decreased ability to form a fist with the wrist in flexion* * **Passive Insufficiency:** Restriction of joint range of motion when fully stretched * *Decreased ROM for wrist extension with the fingers extended*

Answer 186

* MU Recruitment * Preloading * Cross-Sectional area * Angle of pennation * Sarcomere and muscle length * Prestretching * Exercise induced muscle damage * Older muscle * Muscle fiber type

Answer 187

* A rigid object pivoted about a fulcrum * Used to transfer a force to a load * Provides a mechanical advantage

Answer 188

MAF: Perpendicular distance from the line of action of the force to the fulcrum

Answer 189

Muscle force draws the opposite ends of a muscle towards each other while resistive force is the force generated by a source external to the body

Answer 190

The ratio of the output force produced by a system to the applied input force

Answer 191

Fulcrum placed between the applied force and the resistant force

Answer 192

A lever for which the muscle force and resistive force act on the same side of the fulcrum

Answer 193

Force is placed between the axis and resistance

Answer 194

The amount of torque a muscle group can generate at a joint

Answer 195

* **Centric** forces result in linear motion only * **Eccentric** (off center) forces always result in rotation

Answer 196

Pair of equal, oppositely directed forces that act on opposite sides of an axis of rotation to produce torque Example: A dancer

Answer 197

* Tension-generating capacity of the muscle tissue, which is in turn affected by: * Muscle cross-sectional area * Training state of muscle * Moment arm ot the muscles crossing the joint (Mechanical advantage), in turn affected by: * Distance between muscle attachment to bone and joint center * Angle of the muscle's attachment to bone

Answer 198

**Torque** produced by a muscle (Tm) at the joint center of rotation is the product of muscle force (Fm) and muscle moment arm

Answer 199

The **mechanical advantage** of the biceps bracchi is maximum when the elbow is at approximately **90 degrees**, because **100% of muscle force is acting to rotate the radius**

Answer 200

* Point at which a body's weight is equally balanced in all directions * Point that serves as an index of total body motion * Same as the center of mass

Answer 201

* The body responds to external forces as though all mass were concentrated at the CG * This is consequently the point at which the weight vector is shown to act in a free body diagram

Answer 202

* **Reaction Board:** Specially constructed board for determining the center of gravity location of a body positioned on top of it * **Segmental Method:** Procedure for determining total-body center of mass location based on the masses and center of mass locations of the individual body segment

Answer 203

Bone, muscle and fat have different densities and are unequally distributed throughout the body

Answer 204

Resistance to disruption of equilibrium

Answer 205

Ability to control equilibrium

Answer 206

Area bound by the outermost regions of contact between a body and the support surface

Answer 207

* Increasing body mass * Increasing friction between between the body and the surfaces of contact * Increasing the base of support in the direction of an external force * Horizontally positioning the center of gravity near the edge of the base of support on the side of the external force * Vertically positioning the center of gravity as low as possible * The higher the CG, the greater amount of torque its motion creates about the support surface

Answer 208

* Angular kinematic values are described the same way as linear kinematic values 1. Eccentric force is applied and therefore torque is present 2. There is a specified axis of rotation 3. A segment rotating around an axis may have the ability to travel completely in a circle

Answer 209

* Angle at a joint formed between the longitudinal axes of adjacent body segments * The straight, fully extended position at a joint is regarded as zero degrees * The relative angle at the lead knee tends to be smaller during sprinting than during distance running * When joint ROM is quantified, it is the relative joint angle that is measured

Answer 210

* Angular orientation of a body segment with respect to a fixed line of reference * Reference lines are usually vertical or horizontal * The absolute angle of the trunk with respect to vertical is often a quantity of interest in studies of lifting as related to low back pain

Answer 211

The distance from the origin, and the angle between the chosen reference axis and the line formed by connecting the given point to the origin

Answer 212

The center of rotation at a given joint angle, or at a given instant in time during a dynamic movement

Answer 213

Once the angular position is established, we have a reference position from which to measure angles and changes in motion

Answer 214

* Change in angular position of a segment or any point on the rotating segment * The directed angular distance from initial to final angular position * The vector equivalent of angular distance

Answer 215

Degrees or radians

Answer 216

* The size of the angle subtended at the center of a circle by an arc equal in length to the radius of the circle * Unit of angular measure used in angular-linear kinematic quantity conversions: **1 radian = 57.3º**

Answer 217

* The rate of change in angular position * Measured in units of degrees/sec or radians/sec * Angular velocity = Angular displacement/time

Answer 218

* The **rate of change in angular velocity** * Measured in units of deg/s²or rad/s²

Answer 219

* Oriented perpendicular to the lintear displacement of a point on a rotating body

Answer 220

The larger the radius of rotation (r), the greater the linear distance (s) traveled by a point on a rotating body

Answer 221

The acceleration of a body in angular motion can be resolved into two perpendicular linear acceleration components: * Tangential Acceleration * Centripetal Acceleration

Answer 222

* Component of acceleration of angular motion **directed along a tangent** to the path of motion * Represents **change in linear speed**

Answer 223

Tangential acceleration is a measure of **how the tangential velocity of a point** at a certain radius changes with time Just like linear acceleration but its particular to the tangential direction

Answer 224

* Linear acceleration directed toward the axis of rotation * Represents change in direction

Answer 225

* Rotational analog of linear momentum * Moment of inertia about it's axis * Distribution of mass with respect to the axis or rotation * Angular velocity of the body

Answer 226

Kg · m²/s

Answer 227

Sum of angular momenta of individual segments

Answer 228

Segments angular momentum about its own segmental CG

Answer 229

Segments angular momentum about its total body CG

Answer 230

* The angular momentum of an object remains constant unless a net external torque is exerted on it * Newton's first law does not require that the angular velocity be constant

Answer 231

* The change in angular momentum of an obejct is proportional to the net external toruque exerted on it, and this change is in the direction of the net external torque * The net external torque exerted on an object is proportional to the rate of change in angular momentum

Answer 232

* Transfering angular velocity * Changing total body axis of rotation * Asymmetrical arm movements * Rotation of the hips

Answer 233

* Dependent only on the magnitude and direction, but also on the length of time * Linear impulse = Ft * Angular impulse

Answer 234

For every torque exerted by one object on another, the other object exerts an equal torque back on the first object but in the opposite direction

Answer 235

* A substance that flows or continuously deforms when subjected to a shear stress * Both liquids and gases are fluids * Air and water are fluids that commonly exert forces on the human body

Answer 236

Velocity of a body with respect to the velocity of something else, such as the surrounding fluid * Wind, water

Answer 237

Characterized by smooth, parallel layers of fluid * Like cyclist apparel that reduces drag

Answer 238

Flow characterized by mixing of adjacent fluid layers * High pressured fluid mixing with low pressure fluid

Answer 239

* Density - Ratio of mass to volume * Specific weight or specific gravity * Ratio of the weight of an object to the weight of an equal volume of water * Salt-water vs. fresh-water * Viscosity - internal resistance of a fluid to flow

Answer 240

* A fluid force with * Magnitude * Direction * Point of application being a body's center of volume

Answer 241

* The buoyant force acting on a body is equal to the weight of the fluid displaced by the body: * Buoyant foce = displaced fluid volume x fluid specific weight * F_b = V_dY

Answer 242

* Floating occurs when the buoyant force is greater than or equal to body weight * Sinking occurs when body weight is greater than the buoyant force * The equation of static equilibrium for vertical force can be used to answer the question

Answer 243

m = 22 kg V = 0.025 m3 fluid specific weight = 9810 N/m3 F_{b (buoyant force) = fluid displaces volume -->}(0.025 m3)(9810 N/m3) = 245.25 N = critical point then determine weight wt = (22 kg)(9.81 m/s2) = 215. 82 N - she will float

Answer 244

* A force caused by the dynamic action of a fluid that acts in the direction of the free stream fluid flow * Generally a resistance force that tends to slow the motion of a body moving through a fluid

Answer 245

* Drag force * The coefficient of drag * Fluid density * Body surface area that is perpendicular to the fluid flow * Relative velocity of the body with respect to the fluid

Answer 246

* Drag derived from friction in adjacent layers of fluid near a body moving through the fluid * AKA surface drag and viscious drag * Swimmers shave body, wear certain types of swimsuits

Answer 247

* Relative velocity of fluid flow (velocity of fluid over the skin) * Surface area of the body over with the flow occurs (bigger or smaller swimmer) * Roughness of the body surface * Viscosity of the fluid

Answer 248

Derived from a pressure differential between the lead and rear sides of a body moving through a fluid. (kind of like turbulent flow) - boat going through water, high pressure at the front, low pressure at the back AKA profile drag or pressure drag

Answer 249

* The relative velocity of fluid flow * The magnitude of the pressure gradient between the front and rear ends of the body * The surface area of the body perpendicular to the fluid flow

Answer 250

Golf balls with dimples travel further because air wraps around smooth golf balls and not dimpled balls

Answer 251

Drag derived from the generation of waves at the interface between two different fluids, such as air and water \*increased wave drag due to the air and water mixing

Answer 252

* Vertical oscillation of the body with respect to the fluid (swimmers looking up in the water and is more vertical than horizontal) * Relative velocity of the body in the fluid

Answer 253

* A force acting on a body in a fluid in a direction perpendicular to the fluid flow * Generally a resistance force that tends to slow the motion of a body moving through a fluid

Answer 254

* Force of lift * Coefficient of force * Fluid density * Body surface area perpendicular to the fluid flow * Relative velocity of the body

Answer 255

A shape capable of generating lift in a fluid (Surfboard)

Answer 256

Lift generated by a foil is directed from the region of relative **high pressure** on the **flat side** of the foil toward the region of **relative low pressure on the curved** side of the foil

Answer 257

* An expression of the _**inverse relationship** between relative velocity and relative pressure in a fluid flow_ * Regions of **low relative** velocity are associated with relative **high pressure** * Regions of **high relative velocity** are associated with relative **low pressure**

Answer 258

* Pressure * Specific weight of the fluid * Elevation * Relative velocity * Acceleration of gravity * A constant

Answer 259

* Deviation in the trajectory of a spinning object toward the direction of the spin * Results from the magnus force * Throwing a curve or kicking a curve, "bending" * Due to the pressure differential causing the bending in the object during trajectory

Answer 260

Results from a pressure differential created by a spinning body * Topspin - relative low velocity flow, relative high pressure on top and relative high velocity flow and relative low pressure on the bottom of the ball, magnus force directed downward * Backspin - relative high velocity flow and relative low pressure on the top, relative low velocity flow and relative high pressure from the bottom, magnus force directed upward

Answer 261

* Represents an objects mass distribution with respect to a given axis of rotation * Units of moment of inertia consist of mass multiplied by units of length squared (kg x m²)

Exam 1 Flashcards

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