Section 5: Biomechanical principles and levers

Question 1

Definition of linear motion

Answer 1

motion in a straight or curved line, with all body parts moving the same distance at the same speed in the same direction

Question 2

What is inertia?

Answer 2

the resistance an object has to a change in its state of motion

Question 3

State Newton’s first law of inertia

Answer 3

a force is required to change the state of motion

‘every body continues in its state of rest or motion unless compelled to change by external forces exerted upon it’

Question 4

State Newton’s second law of acceleration

Answer 4

the magnitude and direction of the force determines the magnitude and direction of acceleration
‘the rate of momentum of a body is proportional to the force causing it and the change that takes place in the direction in which the force acts

Question 5

State Newton’s third law of motion

Answer 5

for every action there is an equal and opposite reaction

Question 6

What is ground reaction force?

Answer 6

the equal and opposite force exerted on a performer who applies a muscular force on the ground

Question 7

What is the centre of mass?

Answer 7

the point of balance

Question 8

What is the line of gravity?

Answer 8

the line extending vertically downwards from the centre of mass

Question 9

What factors affect stability?

Answer 9

• the height of the centre of mass
• position of the line of gravity
• area of the support base
• mass of the performer

Question 10

What 3 components make up a lever system?

Answer 10

-fulcrum, effort, load

Question 11

Explain each component of a lever system

Answer 11

fulcrum= the point about which a lever rotates
resistance= the weight to be moved by the lever system
effort= the force applied by the user (muscle) of the lever system

Question 12

What is a first class lever?

Answer 12

The fulcrum lies between the effort and resistance

123,FLE

Question 13

What is a second class lever?

Answer 13

The resistance/load is in between the fulcrum and effort

Question 14

What is a third class lever?

Answer 14

The effort is in between the fulcrum and resitance

Question 15

What are force and resistance arms?

Answer 15

Force arm= the length of the line between where the fulcrum and effort are labelled
Resistance arm= the length of the line between where the fulcrum and resistance are labelled

Question 16

What is a mechanical advantage?

Answer 16

Where the force arm is longer than the resistance arm

Question 17

What is a mechanical disadvantage?

Answer 17

Where the resistance arm is longer than the force arm

Question 18

Which type of lever has a mechanical advantage?

Answer 18

2nd class

-generates large amounts of force e.g. pushing up on your toes

Question 19

Which type of lever has a mechanical disadvantage?

Answer 19

1st and 3rd class

-can’t apply lots of force e.g. triceps extension of the elbow and bicep flexion

Question 20

Give an example of Newton’s first law/law of inertia

Answer 20

a ball remains at rest until it is hit, thrown or kicked. tackling a rugby player that is bigger than you, they won’t move because they have a larger inertia

Question 21

Give an example for Newton’s second law/law of acceleration

Answer 21

the harder you kick a ball in one direction the further it will travel in that same direction

Question 22

Example of Newton’s third law (action/reaction)

Answer 22

a sprinter pushes back on the blocks (action) and the blocks push the athlete forwards (reaction) which provides the athlete with acceleration- called ground reaction force

Question 23

What is an example where factors affecting the centre of mass are used in sport?

Answer 23

a sprinter at the start keeps the line of gravity over the base of support at the on your marks. Then as the set is called they move this forward to the edge of the base. This means that on the gun as their hands move away they will fall forward into a running position

Question 24

Give an alternative example where factors affecting the centre of mass are used in sport?

Answer 24

a rugby player going into contact keeps their centre of mass and therefore bodyweight low so that they are harder to move

Question 25

Examples of first class levers

Answer 25

• lifting your head off you chest

- tricep extension over your head

Question 26

Example of a second class lever

Answer 26

-pushing up on your toes e.g. in ballet

Question 27

Examples of third class levers

Answer 27

• bicep curl

- kicking a ball