Unit 3 Biomechanics

Question 1

Newton’s first law

Answer 1

Body will continue in state of rest or constant velocity unless a resultant for a acts upon it

Question 2

Newton’s second law

Answer 2

The rate of change of momentum is proportional to the size and direction of the resultant force

Question 3

Newton’s third law

Answer 3

Every action has an equal and opposite reaction

Question 4

Balanced forces

Answer 4

Equal in size but opposite in direction

Question 5

Unbalanced forces

Answer 5

Unequal in size and opposite in direction

Question 6

Weight

Answer 6

The gravitational pull that the earth exerts on a body

Question 7

Reaction

Answer 7

An equal and opposite force exerted on a body in response to the action created by it

Question 8

Friction

Answer 8

The force that opposes the motion of two surfaces in contact

Question 9

Air resistance

Answer 9

The force opposes the motion as a body travels through the air

Question 10

Free body diagram

Answer 10

Centre of Mass
(Weight) Downward
(Air resistance) Backward

Point of contact on ground
(Friction) Forward
(Reaction) Upward

Question 11

Factors affecting friction

Answer 11

Temperature -> warming up tyres increases friction.

Surface characteristics -> rough or smooth (wearing studs)

Question 12

Centre of mass

Answer 12

The point at which the body is balanced in all directions

Question 13

Factors affecting position of the centre of mass

Answer 13

Distribution of body mass

Shape of the body

Question 14

Factors affecting stability

Answer 14

Height of Centre of Mass
-> lower = better

Mass of body
-> larger = better

Line of gravity
-> above base of support = better

Points of contact
-> more = better

Base of support
-> large = better

Question 15

Factors affecting air resistance

Answer 15

Surface characteristics
-> smooth

Size of surface area
-> small

Shape of body
-> aerofoil

Velocity
-> (fast=drag)

Question 16

Calculations

Answer 16

Velocity
Displacement/time

Acceleration
(Velocity1-Velocity2)/time

Momentum
Mass x Velocity

Force
Mass x Acceleration

Weight
Mass x gravity

Question 17

Lever system (LOAD)

Answer 17

Weight

Question 18

Lever system (EFFORT)

Answer 18

Force applied by our muscle to move the lever

Question 19

Lever system (FULCRUM)

Answer 19

Pivot point (joint)

Question 20

Lever system (LEVER)

Answer 20

The bone

Question 21

Lever system (EFFORT ARM)

Answer 21

Distance between effort and fulcrum

Question 22

Lever system (LOAD ARM)

Answer 22

Distance between load and fulcrum

Question 23

1st class lever system

Answer 23

(Seesaw)

     la          ea  

______________________lever
| /\ |
L F E

• Heading the ball (Neck)
• Overarm throw (Shoulder)

Question 24

2nd class lever system

Answer 24

(Wheelbarrow)

              ea           E
    |
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_lever
   /\|            
   F     la    L

-Sprint start (plantar flexion)

Question 25

3rd class lever system

Answer 25

ea     E
    |
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_lever
   /\|            
   F            la           L

-Bicep curl (flexion at the elbow)

Question 26

Limb kinematics

Answer 26

Use of 3D/optical motion analysis to study movement in relation to time and space.

• > improve technique
• > specific limb/joint movement
• > measure velocity and acceleration

(golfing/sprinting technique)

Question 27

Force plates

Answer 27

A plate used to measure ground reaction forces.

• > analyse the amount of force you can generate
• > can be used for injury rehabilitation
• > analyse running posture

(rugby/sprinting technique/high jump)

Question 28

Wind tunnels

Answer 28

A chamber that measures air resistance acting on an object.

• > Improve air flow around an object
• > Create less drag to increase velocity

(track cycling/Formula 1)

Question 29

Advantages and disadvantages (2nd class lever systems)

Answer 29

Advantages:

• Requires less effort to move an equivalent load.
• Effort arm is larger than load arm.

Disadvantages:

• Moves a smaller distance.
• Lower velocity/acceleration.

Question 30

Advantages and disadvantages (3rd class lever systems)

Answer 30

Advantages:

• Moves a larger distance.
• Larger velocity/acceleration.

Disadvantages:

• Requires more effort to move an equivalent load.
• Load arm is larger than effort arm.