Fundamentals of Biomechanics - Week 2

Question 1

What are the two branches of biomechanics?

Answer 1

kinematics and kinetics

Question 2

What is kinematics?

Answer 2

variables that describe movements (displacement, velocity, acceleration)

Question 3

What are the two types of kinematics?

Answer 3

linear and angular

Question 4

What is kinetics?

Answer 4

forces that cause movements

Question 5

What are the two types of kinetics?

Answer 5

linear force and angular torque

Question 6

What is the difference between a scalar and vector quantity?

Answer 6

Scalar = magnitude only, eg mass, distance, speed, time
Vector = magnitude and direction, eg force, displacement, velocity, acceleration

Question 7

What is a scalar? Give an example

Answer 7

mass, distance, speed, time

Question 8

What is a vector? Give us an example

Answer 8

force, displacement, velocity, acceleration

Question 9

What are the three types of motion?

Answer 9

linear, angular and general

Question 10

What is linear motion? Give an example.

Answer 10

translatory motion

Question 11

What is angular motion? Give an example

Answer 11

rotation around an axis

Question 12

What is general motion? Give an example

Answer 12

combination of both linear and angular

Question 13

What is linear displacement? What is it measured in?

Answer 13

change in location from initial to final position; must include direction and distance in metres

Question 14

How is linear displacement different to distance?

Answer 14

distance is the route taken, whereas displacement is a straight line drawn from the initial to final points

Question 15

What is linear velocity? What is the formula?

Answer 15

the rate of change in displacement

velocity (v) = change in displacement (s)/change in time (t)

Question 16

What is the difference between speed and velocity?

Answer 16

speed is how fast a person or object is going, it is scalar (magnitude only)
velocity is speed in a given direction, it is a vector (magnitude and direction)

Question 17

Can you have negative velocity?

Answer 17

yes, it means movement in the opposite direction

Question 18

How is instantanous velocity different to under-estimate average velocity?

Answer 18

more accurate calculation, the smallest point of time is isolated to work out linear velocity.

Question 19

What is the first central differenceformula?

Answer 19

velocity in an instant = (displacement at frame AFTER instant - displacement at frame BEFORE instant) / (time at frame AFTER instant - time at frame BEFORE instant)

Question 20

What is linear acceleration?

Answer 20

the rate of change in velocity

Question 21

What is the formula for linear acceleration?

Answer 21

acceleration (a) = change in velocity (v)/change in time (t)

Question 22

When is acceleration 0?

Answer 22

• at max velocity
• at rest
• when velocity is contant

Question 23

What is force?

Answer 23

• pushes and pulls
• all movement ceases and occurs due to the action of forces
• acceleration and change in direction of an object
• stabilises the body
• measured in Newtons (N)
• vector - has magnitude and direction

Question 24

What are the properties of a force?

Answer 24

• magnitude (N) - amount of force exerted
• point of application - where force is applied
• direction (in degrees or rad)
• line of action - path of the force

Question 25

What are Newtons three laws of motion?

Answer 25

1: law of inertia 2: law of acceleration 3: law of reaction

Question 26

Explain Newton's first law of motion?

Answer 26

a body will remain at rest or in constant motion unless acted upon by a net external force eg man on motorcycle won't stop flying through the air unless a force hits him (fence, gravity, wind)

Question 27

What is Newton's second law of motion?

Answer 27

the change in motion of an object is propertional to the force impressed; and is made in the direction of the straight line in which it is impressed force = mass x acceleration

Question 28

What is Newton's third law of motion?

Answer 28

to every action there is an equal and opposite reaction

Question 29

What are the forces acting on the body?

Answer 29

weight due to gravity, muscle, reaction forces (ground reaction forces, joint reaction forces), friction, spring force, bouyancy, air resistance

Question 30

What is mass?

Answer 30

the amount of 'matter' an object has, constant regardless of where you are, scalar, measuresd in kg

Question 31

What is weight?

Answer 31

the force experienced by an object due to gravity | weight = mass x acceleration due to gravity (9.81m2), measured in Newtons (N), vector (direction is always down)

Question 32

What is the formula for weight?

Answer 32

weight = mass x 9.81

Question 33

Where are muscle forces exerted?

Answer 33

muscle forces are exerted at the point of application (origin/insertion)

Question 34

What is the ground reaction force?

Answer 34

action force = weight force | weight = mass x acceleration due to gravity

Question 35

How is breaking force reduced?

Answer 35

foot should fall under the body or behind the body so that the person is propelled forward

Question 36

What are types of mechanical loading in the body?

Answer 36

compression, tension, shear, torsion, bending