Introduction to Biomechanics (Biomechanics I)

Question 1

Define Biomechanics

Answer 1

The study of the structure and functions of biological systems by means of the methods of mechanics

Question 2

Biomechanics is the “physics of bodily movement” involving

Answer 2

• Solid Mechanics
• Fluid Mechanics
• Continuum Mechanics

Question 3

Define Sports Biomechanics

Answer 3

By understanding and applying mechanical concepts, determine the optimal way to move the body in order to achieve maximal performance and minimizing risk of injury

Question 4

Define Occupational Biomechanics

Answer 4

The goal is to design machines in the workplace to reduce repetitive stress on workers’ spines/joints

Question 5

Define Clinic Biomechanics

Answer 5

Clinical biomechanists analyze the mechanics of patients and provide feedback (biofeedback) to restore normal function

Question 6

FUN FACT: Cellular Biomechanics also exists

Answer 6

Example like Breast Cancer Cell migration

Question 7

Mechanics is divided into what 2 concepts?

Answer 7

• Statics
• Dynamics

Question 8

Define Statics

Answer 8

• Study of systems that are in a constant state of motion, whether at rest with no motion or moving at a constant velocity without acceleration
• Involves all forces acting in EQUILIBRIUM!!!

Question 9

Define Dynamics

Answer 9

• Study of systems in motion with acceleration
• System in acceleration is UNBALANCED due to unequal forces acting on the body.

Question 10

Define Kinematics. Provide 3 examples!

Answer 10

• Kinematics: Study of the variables that describe or quantify motion
• Ex.) Displacement, Velocity, and Acceleration

Question 11

Define Kinetics. Provide 3 examples!

Answer 11

• Kinetics: Study of the variables that cause or influence motion
• Ex.) Forces, Torques, and Mass

Question 11

Compare Vectors and Scalars. Provide examples!

Answer 11

• Vectors: Both magnitude and direction
• Ex.) Displacement, Direction, Velocity, Acceleration, Momentum, Force, Lift, Drag, Thrust, and Weight
• Scalar: Only magnitude
• Ex.) Length, Area, Volume, Speed, Mass, Density, Pressure, Temperature, Energy, Entropy, Work, Power

Question 12

In the formula F=ma, what quantity is scalar and which one is vector?

Answer 12

• Force= Vector
• Mass= Scalar
• Acceleration= Vector

Question 13

Describe Force

Answer 13

• Vector quantity
• A physical quantity which causes or tends to cause a change in the motion or shape of a body
• A push or pull

Question 14

What are 4 properties of Force?

Answer 14

1. Magnitude: How much force is applied?
2. Direction: In what direction is the force applied?
3. Point of application: Each force is considered to act at one point.
4. Line of Action: The line is a straight line which extends infinitely along the direction of the force.

Question 15

The skeletal system is subjected to a variety of different forces so that bone is loaded in various directions. These are loads produced by gravity, weight-bearing, muscle, and external forces in what 4 concepts?

Answer 15

1. Compression
2. Tension
3. Shear
4. Mechanical Stress

Question 16

Describe Compression

Answer 16

A compressive force presses the ends of the bones together and is produced by muscles, weight-bearing, gravity, or some external loading down the length of the bone

Question 17

Describe Tension

Answer 17

• Pulling force that creates tension in the object/body
• Tends to lengthen and narrow
• Source is usually muscle

Question 18

Describe Shear Stress

Answer 18

Arises from the force vector component parallel to the cross section

Question 19

Describe Normal Stress

Answer 19

Arises from the force vector component perpendicular to the cross section

Question 20

Define Stress

Answer 20

Load per cross-sectional area

Question 21

Define Strain

Answer 21

• Deformation with respect to the original length of the material
• There is normal strain and shear strain (defined in next two cards)

Question 22

Define Normal Strain

Answer 22

Change in Length

Question 23

Define Shear Strain

Answer 23

Change in Angle

Question 24

What is the Free-body diagram?

Answer 24

Stick figure drawing of the system being analyzed on which the vector representations of the external forces acting on the system are drawn

Question 25

Define MASS Is it the same anywhere in the universe?

Answer 25

Measure of the quantity of matter (KG) Yes! It is the same.

Question 26

Define Weight What formula is associated with weight?

Answer 26

Measure of force (pull of gravity on a mass). Varies depending on gravitational pull W=mg (mass * gravity)

Question 27

Define Gravity and the value associated with it

Answer 27

Downward acceleration of an object due to gravity 9.8 m/sec^2

Question 28

Define Centre of Mass

Answer 28

- An imaginary point where the total mass of the body is considered to be centered - Balance point where the mass of athletes for instance is thought to be concentrated

Question 29

Define Inertia

Answer 29

- Body or objects RESISTANCE to a change in motion - A change in motion may refer to trying to start something moving, stop it moving, or change it from moving at constant speed

Question 30

What is the 1st Law of Motion?

Answer 30

- INERTIA!!!! - A body at rest or in uniform (linear or angular) motion will remain at rest or in motion unless acted upon by an external force or torque - Ex.) Whiplash injuries

Question 31

What is the 2nd Law of Motion?

Answer 31

- A force or torque acting on a body will produce an acceleration proportional to the force or torque - Ex.) F=ma - Ex.) T=la

Question 32

What is the 3rd Law of Motion?

Answer 32

- For every action there is an equal and opposite reaction (torque and/or force) - Contact forces: Ground Reaction Force (GRF)

Question 33

Define Displacement

Answer 33

- Vector - Length and Direction of a line joining the initial position with the final position

Question 34

Compare Speed and Velocity

Answer 34

- Speed: Refers to how fast something is traveling. Magnitude NOT involved! - Velocity: Both magnitude and direction. How fast something is going and in what direction they are moving.

Question 35

Define Acceleration

Answer 35

- Defines how much an object is speeding up or slowing down - If an object or body is in a state of constant velocity, or a state of equilibrium then the acceleration is equal to zero - Vector quantity!

Question 36

What formula is involved in Pressure? What unit is used?

Answer 36

- P=F/A (distribution of force over an area) - P= Pressure - F= Force (N) - A= area (m^2) - 1 Pascal = 1 N/m^2

Question 37

What are the 3 Physical Principles Influencing Pulmonary Ventilation

Answer 37

1. Air flows from areas of higher to lower pressure - If pressure is higher on one end of the tube, then at the other end air will flow down its pressure gradient 2. Changes in volume result in changes in pressure - As volume inc in closed container, pressure decreases AKA Boyle's Law 3. Changes in tube diameter result in changes in resistance - Poiseuille's Law: Resistance to airflow is proportional to diameter of a tube raised to the fourth power

Question 38

Define Viscosity

Answer 38

Resistance that a fluid offers to flow when subject to a shear

Question 39

If the fluid is incompressible, then inertia becomes ____, and if fluid has NO friction (no slip condition) the viscosity becomes ____

Answer 39

- ZERO (0) - ZERO (0)

Question 40

What formula is associated with Navier Stokes

Answer 40

Inertia = (-)Pressure Gradient + Body Force + Viscosity