Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biomechanics > Definitions > Flashcards

Definitions Flashcards

(90 cards)

Start Studying
1
Q

Kinetics

A

concerning the analysis of the forces acting on the body. (BASES)
“The study of the action of forces” Hall, 2012
“The branch of dynamics concerned with the forces that cause or tend to cause motion.” McGinnis, 2013

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Kinematics:

A

concerning the analysis of the movements of the body. (BASES)
“The study of the description of motion including consideration of space and time.” (Hall, 2012)
“The branch of dynamics concerned with the description of motion.” (McGinnis, 2013)
A force is a push or a pull. A force accelerates or deforms (not in rigid-body mechanics) an object. Forces come in pairs: action and reaction. A force is something that can cause an object to accelerate (start, stop, speed up, slow down, or change direction). A force is known as a vector quantity (size and direction).
Characteristics: point of application, direction and its sense. (McGinnis, 2013)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Internal forces

A

forces that act within the object or system whose motion is being investigated. Internal forces are important if concerned with the nature and causes of injury, but they cannot produce any changes in the motion of the body’s centre of mass. Muscles can only produce internal forces, even though muscle forces can produce motion on the body’s limbs, but these motions will not change the motion of the body’s centre of mass unless external forces are acting on the system. (McGinnis, 2013)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

External forces:

A

forces that act on an object as a result of its interaction with the environment surrounding it:
Non-contact forces (gravity).
Contact forces (air resistance, water resistance, ground…):
• Perpendicular component (normal reaction force): acting perpendicularly to the surface of contact
• Parallel component (friction): acting parallel to the surface of contact and opposes motion or sliding between the surfaces. (McGinnis, Chpt 1, 2013)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

FRICTION

A

Friction arises when molecules of the surface are in contact and are interacting:

Friction force is proportional to the normal contact force and acts perpendicular to it e.g. pushing a book then adding another book on top. Adding weight (not mass!) would increase the normal contact force acting between the 2 surfaces but it would also increase the interactions of the molecules of the contacting surfaces, because they would be pushed together harder.
Friction is not affected by the size of the surface area e.g. if you stand the book on the table. The increase in the surface area increases the number of molecular interactions, but the decrease in pressure (force divided by area) decreases the magnitude of these interactions. Thus the net effect of increasing surface area is zero, and friction is unchanged.
The nature of the materials in contact affect the friction force between them e.g. placing a shoe compared to a book. The weight and mass of the objects are the same but the surface area changed. However that doesn’t affect the friction. So it is the difference in the type of material (soft and rough).
Static friction is greater than dynamic friction. It is harder to start something to get moving than to keep the object moving. (McGinnis, Chpt 1, 2013)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Colinear forces

A

are forces that have the same line of action. E.g. tug-of-war

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Concurrent forces:

A

are forces that do not act along the same line but do act through the same point.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Static equilibrium

A

when an object is at rest and the forces are in equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

A free-body diagram:

A

it is a mechanical representation and a useful tool for analyses. Only the object is drawn with all the external forces that act on it. (McGinnis, Chpt 1, 2013)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Compressive forces:

A

pushing forces act on the ends of an internal structure and the structure is under compression. (McGinnis, 2013)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Tensile forces:

A

pulling forces act on the ends of an internal structure and the structure is under tension (McGinnis, 2013)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Inertia:

A

the property of an object that resists changes in motion. Linear inertia is quantified as an object’s mass. Thus it is more difficult to speed up, slow down, or change the direction of a more massive object because it has more linear inertia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Angular inertia

A

(rotary inertia): the property of an object that resists changes in its angular motion. It is more difficult to speed up, slow down, or change the direction of an object with more angular inertia (mass). Angular inertia is affected by mass and how the mass is distributed relative to the axis of rotation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Angular momentum:

A

is the product of mass and velocity. Mathematically, angular momentum is a vector quantity, it has a size and direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Scalar

A

A quantity that has only a magnitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Speed

A

The rate of change of displacement with respect to time (vector quantity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Velocity

A

The rate of change of distance with respect to time (scalar quantity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

vector

A

a quantity that has both direction and magnitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

acceleration

A

the rate of change of velocity with respect to time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

displacement

A

change in position during a time interval (vector quantity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Distance

A

length along a path an object has travelled (scalar quantity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

mass

A

the quantity of matter in an object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

weight

A

the force that results from the action of a gravitational field on a mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Force

A

A force is a push or a pull
A force accelerates an object.
Equation: F = m x a
Units: Newtons (N)
One Newton of force is defined as the force required to accelerate a 1 kg mass, 1 m/s2.
A force is a vector – it has a size (magnitude) and a direction.
Length of arrow indicates size.
Shaft/arrow indicates the direction and point of application.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Inertia
the property of an object to resist changes in its motion
26
Linear motion
movement along a straight or curved line where body parts move in the same distance and direction at the same time (a.k.a translation) e.g. skating
27
angular motion
motion around an imaginary axis with all body parts moving through the same angle at the same time (a.k.a rotation) e.g. gymnast swinging on bar
28
Angular velocity
the rate of change of angular displacement with respect to time
29
Curvilinear motion
the body moves along a curved path and still satisfies the condition of linear motion e.g. sky diving
30
General motion
very common in sport, usually rotation of some body parts resulting in translation of other body parts
31
Magnitude
The relative size of an object. The term for the size of a vector.
32
Stability
Resistance to both linear and angular acceleration to disruption of equilibrium.
33
Centre of Mass (CoM)
the point in a body or a system of bodies about which the weight is evenly distributed or balanced and through which the force of gravity acts.
34
Momentum (P)
The product of mass and velocity of an object.
35
Perspective error (2D Video Analysis)
The distance between the performer and the camera. Errors: If the object is behind the Plane of Motion (PoM) then the dimensions will be smaller. If the object is in front of the PoM then the dimensions will be larger. If the object is not parallel to the PoM then the angle and length of object will be wrong To reduce error: Increase the distance between the camera and the PoM. Place the object parallel to the PoM.
36
Newton's first law
the law of INERTIA: an object either remains at rest or continues to move at a constant velocity, unless acted upon by a net force
37
Newton's second law
the law of ACCELERATION: the sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration a of the object: F = m x a
38
Newton's third law
the law of REACTION: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
39
Running speed
step rate (Hz) x step length (m)
40
Projectile
a projectile is an object that is subject to no external forces other than gravity. If there is no air resistance, the projectile follows a parabolic path and the path is symmetrical by its APEX.
41
Factors affecting long jump performance
Distance --> flight distance --> HEIGHT, SPEED and ANGLE of takeoff
42
Resultant VELOCITY of a Projectile (i.e. hypotenuse in trigonometry)
Remember that RESULTANT means the sum of the vectors and that velocity is a vector. A projectile has a HORIZONTAL AND VERTICAL velocity. This means 2 VECTORS... so this can be calculated by using basic trigonometry: you can either use the Pythagorean theorem wich is a quicker and easier than using the SOHCAHTOA equation
43
Take off ANGLE of a projectile
This is the ANGLE at which the Centre of Gravity (CG) is projected: Using basic trigonometry, this can be calculated by using the equation: Arctan (vertical Take off velocity/Horizontal Take Off Velocity)
44
What is the vertical acceleration of a projectile?
The vertical acceleration of a projectile is CONSTANT due to gravity (i.e. 9.8m/s2)
45
What is the vertical velocity of a projectile?
The vertical velocity of a projectile is CONSTANTLY CHANGING during its flight. Indeed, velocity = displacement x time
46
What is the horizontal acceleration of a projectile?
There is NO horizontal acceleration of a projectile during flight.
47
What is the horizontal velocity of a projectile?
Air resistance can affect horizontal velocity. In most cases, the horizontal velocity of a projectile remains CONSTANT
48
Vertical Motion is motion with constant..........., while horizontal motion is motion with constant...........
acceleration ; velocity
49
Projectile motion occurs when objects are only under the influence of.......... and..........
gravity ; air resistance
50
The height of a projectile depends on..........
Initial Vertical Velocity
51
The time of flight of a projectile depends on..........
Initial Vertical Velocity
52
Horizontal motion of a projectile depends on..........
horizontal velocity and time of flight
53
The Trajectory of a projectile is influenced by........
1. projectile speed 2. Height of release (i.e. projectile height) 3. projectile angle
54
Apex
Point of Maximum Height of a projectile. | Vertical Velocity at Apex = 0
55
SUMMARY of the Kinematics of Projectiles Projectile motion
A projectile ignores air resistance, therefore only gravity affects it (i.e. vertical acceleration -9.81m/s2), the object follows a symmetrical (by its Apex) parabolic path. The projectile motion describes the path of the centre of mass (CoM) of the object. - Horizontal velocity = the same - Horizontal acceleration = 0 - Vertical velocity before the Apex = positive and constantly changing - Vertical velocity after the Apex = negative and constantly changing - Vertical velocity at the Apex = 0 *Horizontal and vertical motion are independent of each other
56
What does EAUM stand for? | In the three equations... what will always be the same?
``` Equation of Uniformly Accelerated Motion Only apply it to projectiles In sport such as throwing events, jumping, gymnastics, etc... In the Equations: vertical acceleration (g) = -9.81 m/s2 horizontal acceleration = zero Vertical acceleration = constantly changing vertical velocity at the apex = 0 horizontal velocity remains constant ```
57
Range (R) of a projectile = .........(2 ways)
R = horizontal velocity x time of flight This is from EAUM 2nd equation: displacement of body = initial velocity of body x time involved or R = initial velocity x cos Alpha (angle of projectile) x time of flight
58
If an object takes off and lands from the same height and time of flight..... what will be the equation? Remember that the projectile will be symmetrical by the apex so therefore Tup = Tdown
T = Tup + Tdown Tup = V x sin Omega (angle of projection) / gravity Tup = Tdown ==> that makes 2x Therefore T = 2x (V x sin Omega / gravity)
59
The effect of landing height from a projectile: If the height of release is greater than the height of landing (h = +ve), the optimal angle is........... If the height of release is lower than the height of landing (h = -ve), the optimal angle is..........
<45 degrees ; >45 degrees
60
Static friction | definition
Also known as Surface or Contact friction: When 2 surfaces are not moving relative to each other. The force which opposes the onset of movement.
61
Dynamic friction | definition
When dry friction acts between 2 surfaces that are moving relative to each other.
62
Sliding friction | definition
The force which opposes the sliding of one body over another.
63
Rolling friction | definition
The force which opposes the rolling of one body over another.
64
laws of friction
Law 1: The force of friction is directly proportional to load (i.e. force perpendicular to the surface) Law 2: The force of friction is independent of the apparent area of contact
65
Mechanical work
The product of force and the amount of displacement along the line of action of that force. There are two types of work: positive and negative work Work = Force x Displacement Units (N/m or Joules)
66
Energy
Energy is the CAPACITY to do work. There are two forms of mechanical energy: 1. Kinetic: energy due to MOTION. 2. Potential: energy due to POSITION or DEFORMATION. It has 2 forms: a) Gravitational Potential Energy: Energy due to the object's POSITION relative to earth b) Strain Potential Energy: energy due to the DEFORMATION of an object.
67
Kinetic energy | equation
Kinetic energy = 1/2 x Mass x Velocity²
68
Gravitational Potential energy | equation
Gravitational Potential energy = Mass x Gravity x Height | Units: Joules or N/m
69
Power | equation
Power = work / time OR (force x displacement) / time Units: Watts
70
Power | definition
The rate of doing work
71
Torque | definition
Also known as Moment, is the rotational effect of an eccentric force
72
Torque | equation
Force x Moment Arm (perpendicular distance) | Units: Nm
73
Angular inertia | definition
Resistance to Angular Motion
74
Angular Momentum | equation
H = I• Ѡ
75
Mass is resistance to..........
linear acceleration
76
Moment of inertia is resistance to..........
angular acceleration
77
what are the 2 factors that affect moment of Inertia
mass | mass distribution around axis of rotation
78
Moment of Inertia | equation
(single mass) I = mr² | (many masses) I = Σmr²
79
Radius of Gyration | definition, practical example and symbol
Radius of Gyration (k): length from axis of rotation to a point where mass of the segment would be concentrated to produce an equivalent moment of inertia Practical example: Sprinting – flexed knee redistributes mass in order to reduce distance of concentration of mass from axis of rotation which therefore reduces radius of gyration. Meaning the leg can be rotated forward faster and individual can run faster. Spinning on chair – tuck in all body parts you will spin faster than if you are spread out. Due to smaller moment of inertia.
80
Body segment | equation
I = mk²
81
Angular momentum | symbol, equation and practical example
H = Moment of Inertia (I) x Angular Velocity (Ѡ) Practical example: A diver performs a piked front somersault by transferring the angular momentum from the upper body to the lower body and vice-versa. Done by altering their body position which therefore alters their moment of inertia.
82
First class lever definition
The applied force and the resistance force are on opposite sides of the fulcrum
83
Second class lever definition
the resistance force is between the applied force and the fulcrum
84
Third class lever definition + mechanical advantage + advantages + limitations
``` the applied force is between the fulcrum and the resistance force mechanical advantage <1 Advantage: maximise speed distance lifted is larger Limitations: Amount of weight lifted is limited requires effort > resistance ```
85
Wheel and Axle-like Arragement definition + examples in the human body
a wheel attached to an axle, both of which rotate about a common axis Can either magnify force or increase the speed of motion – as for levers most maximise speed E.g. Obliques or medial rotation at shoulder
86
The kinetic Link Principle definition
Also known as the Summation of Speed. There is a sequence of acceleration and deceleration of links (segments) from proximal to distal, which results in a tremendous speed at the distal end.
87
Pushlike patterns; describe when it would be used, its characteristics and the path it follows
Used when a large force must be applied or when maximum accuracy of projection is required Is characterised by the body parts moving the object forward from behind the object Takes a rectilinear path, (more in a straight line)
88
Define the Speed-Accuracy Trade Off + examples
In the performance of many skills, the outcome is determined by both speed and accuracy. As the demands for accuracy increases, the speed of the movement decreases. Examples: penalty kick in football, throwing a ball, long jump approach to take-off board
89
what type of movement would be used in throwing to maximise velocity?
Throwlike movement
90
what type of movement would be used in throwing to maximise accuracy
A pushlike motion

Biomechanics (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions