3.1 - Biomechanical principles: Newton's laws of motion, force and use of technology

Question 1

biomechanics definition

Answer 1

study of human movement and the effect of force and motion on sport performance

Question 2

biomechanics allows coaches to:

Answer 2

• analyse performance
• maximise movement efficiency and sport technique
• reduce and prevent injuries
• design and choose correct equipment to satisfy demands of activity

Question 3

newtons 1st law of motion definition + application

Answer 3

body continues to stay in a state of rest or uniform velocity unless acted upon by an external or unbalanced force

• 100m sprinter remains at rest in blocks until internal force large enough to overcome their inertia creates motion

Question 4

newtons second law motion definition + application

Answer 4

• body’s rate of change in momentum is proportional to the size of the force applied and acts in the same direction as the force applied
• greater force applied to sprinter = greater rate of change in momentum = greater acceleration

Question 5

newtons third law of motion + application

Answer 5

for every action force applied to a body, there is an equal and opposite reaction force

• when sprinter applies down and backward action to blocks, blocks provide an equal up and forward force.

Question 6

velocity formula

Answer 6

displacement/time taken

Question 7

momentum formula

Answer 7

mass x velocity
kgm/s

Question 8

acceleration formula

Answer 8

final velocity - initial velocity/ time taken

Question 9

force formula

Answer 9

mass x acceleration

Question 10

two types of force

Answer 10

internal force - generated by contraction of skeletal muscle, eg 100m sprinter contracting rectus femurs to extend knee
external force - comes from outside the body and acts upon it, eg, air resistance, weight, friction

Question 11

what does it mean when resultant forces are not = 0

Answer 11

body will accelerate/decelerate, etc

Question 12

weight formula

Answer 12

mass x acceleration due to gravity(9.81N on earth)

w = r1+ r2

Question 13

what is a reaction force?

Answer 13

the equal and opposite force exerted by a body in response to the action force placed upon it

Question 14

what four factors is air resistance affected by?

Answer 14

• velocity
• shape
• frontal cross sectional area
• smoothness of the surface

Question 15

how do high jumpers maximise reaction force?

Answer 15

• lean back to extend time action force is applied to the track
• arm swings and leg extends (internal force)

Question 16

limb kinematics definition + adv/disadv

Answer 16

3d or optical motion analysis records an athlete performing a sporting action

• accurate, immediate and objective
• coach use to improve technique such as football kick
• depends on correct placement of bodily markers
• expensive and limited to lab conditions

Question 17

force plates definition + adv/disadv

Answer 17

• rectangular plate that measures force applied
• immediate, accurate and reliable results can be used to analyse performance
• specialist, expensive and limited to lab conditions

Question 18

wind tunnels

Answer 18

allow measurement of wind, can change wind velocities to help decide how to streamline an object for maximal performance
- Time efficient
- Can see force and direction of wind
- Specialised facilities
- Expensive and require complex analysis of results by research professionals

Question 19

Zero net force

Answer 19

means acceleration is zero, or object at rest, eg rugby scrum pushing at same force, so no movement

Question 20

Forces

Answer 20

• create motion
• Accelerate a body
• Decelerate a body
• Change direction of a body
• Change shape of a body

Question 21

Friction affected by:

Answer 21

• roughness of ground surface
• Roughness if contact surface (sprinters spikes)
• Temperature - higher = more
• Size of normal reaction

Question 22

Weight + reaction force

Answer 22

Weight - from centre of mass extending vertically downwards
Reaction force - from point of contact extending vertically upwards
If r>w, eg basketballer take off phase - net force is positive = acceleration in upward direction

Question 23

Friction

Answer 23

from point of contact and usually extending horizontally in the same direction as motion

Question 24

Air resistance

Answer 24

from the centre of mass and extending horizontally against the direction of motion