Biomechanical Principles

Question 1

Define and give an example for Newton’s 1st law.

Answer 1

Newton 1/ Law of Inertia
A body will remain in a state of rest or uniform motion unless an external force acts upon it
e.gaccept any suitable example

Question 2

Define and give an example for Newton’s 2nd law.

Answer 2

Newton 2 /Law of Acceleration
The acceleration or rate of change of momentum or velocity of a body is proportional to the size of the force and takes place in the direction in which the force acts
e.gaccept any suitable example

Question 3

Define and give an example for Newton’s 3rd law.

Answer 3

Newton 3 /Law of Reaction
For every action or force there is an equal and opposite reaction
e.gaccept any suitable example

Question 4

Explain what is meant by the term ‘net force’

Answer 4

The sum of all forces acting on a body
Net force is zero if forces are balanced
Net force positive/negative if forces are unbalanced

Question 5

Describe how the force of weight acts on a sporting body (1)

Answer 5

Downward force
Acts from centre of mass
Due to gravity

Question 6

Identifyfourfactors affecting air resistance

Answer 6

Velocity
Shape
Frontal cross sectional area
Surface characteristics
Air density

Question 7

Define the term ‘friction’ and describe, using sporting examples, how performers increase or decrease friction in order to optimise performance. (3)

Answer 7

The resistance to motion of two moving objects or surfaces that touch
Increased roughness of contact surface = increased friction e.g. sprinter wears spikes to increase friction which helps them run faster
Increased roughness of ground surface = increased friction e.g. tarmacadam track in athletics increases friction
Create down force - Spoiler on F1 car applies down force, increasing friction to increase speed
Increased temperature = increased friction e.g. F1 racing warm-up lap.

Question 8

Explain, using practical examples, why some performers would want to maximise friction. (2)

Answer 8

Maximise friction force to accelerate, e.g. sprinter wears spikes to aid grip when accelerating
Maximise friction to slow down/stop, e.g. a skier turns the skis sideways to slow down or stop
Increase friction to change direction, e.g. footballer wears studs to enable them to turn quickly
A performer increases friction to impart spin on an object, e.g. a slice shot in table tennis

Question 9

Define ‘acceleration’ and describethreeways in which a performer can increase their acceleration during sport or physical activity. (3)

Answer 9

Acceleration = rate of change of velocity
(Final velocity – initial velocity) ÷ time taken
Increase force - e.g. a sprinter can apply a greater force to the blocks/track
Increase friction - e.g. a long jumper can wear spikes to increase friction with the ground
Reduce mass - e.g. a high jumper loses weight prior to competition
Improve technique - e.g. a runner adjusts technique
Reduce air resistance e.g. a sprint cyclist adopts a streamlined shape to minimise air resistance

Question 10

Calculate the force applied (1)

Answer 10

Force = mass x acceleration

Question 11

Define the term ‘centre of mass’. (1)

Answer 11

It is the position on a body through which it is balanced in all directions or the point at which the mass of a body is said to be concentrated

Question 12

Explain how a rugby player can apply knowledge of centre of mass to increase their stability. (3)

Answer 12

To maintain stability centre of mass must be over base of support
To increase stability rugby player lowers centre of mass by bending knees
To increase stability player increases area of base by widening stance
Stability is increased if line of gravity is in centre of base of support
Stability is increased if line of gravity is in centre of base of support forwards

Question 13

Describe how a performer applies an eccentric force to a ball and explain its effect (2)

Answer 13

Eccentric force is an off centre force
Force applied outside the centre of mass of the ball
Creates spin / angular motion
Causes deviation in flight

Question 14

Explain the components of a first class lever (3)

Answer 14

Lever- Bones give leverage.
Fulcrum- Point of rotation / Fulcrum is the elbow
Load- Weight / resistance to be moved
Effort - Force applied that causes lever to move
Load Arm - Distance from load to fulcrum
Effort Arm - Distance from effort to fulcrum

Question 15

Critically evaluate the use of 2nd class levers.

Answer 15

Mechanical advantage due to effort being further from fulcrum than load.
Effort arm being greater than load arm.
Very efficient at moving a heavy load.
Sporting eg When jumping gastrocnemius / soleus can move weight of entire body
Move heavy loads only over a small distance

Question 16

Critically evaluate the use of 3rd class levers.

Answer 16

Mechanical disadvantage, due to effort being closer to fulcrum than load.
Load arm being greater than effort arm.
Move speed of load fast
Sporting eg Bicep curl, speed of dumbbell is faster than speed of Biceps Brachii
Struggle to move heavy loads.
Sporting eg Biceps Brachii can only move relatively small loads in Bicep Curl

Question 17

Calculate the torque generated (1)

Answer 17

Moment of force= force x distance from fulcrum
With Units - Nm

Question 18

Explainoneadvantage andonedisadvantage of a class 2 lever system. (2)

Answer 18

Inefficient because it has mechanical disadvantage and will struggle to move heavy loads
Performer can move a load faster than another lever

Question 19

Outlineonesporting situation where a wind tunnel is used to enhance performance,twobenefits of this technology. (3)

Answer 19

Sporting example e.g. cyclist or F1 car or speed skater or downhill skier
Improve technique to reduce drag
Increase streamlining
External factors can be controlled

Question 20

Name the only first order lever in the body

Answer 20

Elbow extension

Question 21

Name the only second order lever

Answer 21

Ankle joint