Force

Question 1

What are the two types of force?

Answer 1

Internal and External

Question 2

Definition of force

Answer 2

A push or pull that alters the state of motion of a body

Question 3

What is force measured in?

Answer 3

Newtons (N)

Question 5

What is an internal force?

Answer 5

Generated by the contraction of skeletal muscle

Question 6

Give a sporting example of a internal force

Answer 6

A 100m sprinter must contract the rectus femoris to extend the knee and gastrocnemius to plantar flex the ankle to generate the force required to drive away from the blocks

Question 7

What is an external force?

Answer 7

Comes from outside the body

Question 8

What are examples of external forces?

Answer 8

Weight, reaction, air resistance, friction

Question 9

What are the five effects of force

Answer 9

1. Can create motion
2. Can accelerate a body
3. Can decelerate a body
4. Can change the direction of a body
5. Can change the shape of a body

Question 10

Explain the 5 effects of force using a football penalty as a sporting example

Answer 10

1. Can create motion - the football will remain at rest on the penalty sport until a force is applied to make it move
2. Can accelerate at body - the greater the force applied by the footballers foot to the ball, the greater the rate of acceleration towards the goal
3. Can decelerate a body - as the ball moves through the air towards the goal, air resistance will act in the opposite direction and slow it down
4. Can change direction of a body - as the goalkeeper dives to save a high corner shot, he will apply a force from his hands to the ball, changing its direction and pushing it away from the goal
5. Can change shape of a body - if the goalkeeper fails to make the save, the force of the ball coming into contact with the net will make the net change shape

Question 11

Does force always have an effect on motion?

Answer 11

No, can be generated and have no effect on the motion of a body. During a plank, the rectus abdominis isometrically contracts generating muscular force, but a static position is maintained

Question 12

Definition of net force

Answer 12

The sum of all forces acting on a body, also termed resultant force. It is the overall force acting on a body when all individual forces have been considered

Question 13

What occurs is the net force = 0?

Answer 13

There will be no change in motion as all forces are balanced, The body will remain at rest or continue to travel at a constant velocity

Question 14

Give a sporting example of when net force = 0

Answer 14

In a rugby scrum with equally weighted packs. If both packs push forwards with equal force the net force will be 0 and there will be no change in motion

Question 15

What happens when a net force present?

Answer 15

There will be a change in motion as the forces are unbalanced. A body will accelerate, decelerate, change its direction or shape

Question 16

What is an example of when net force is present?

Answer 16

When a netballer makes a chest pass, the forward force applied to the ball is greater than any air resistance or gravitational pull and therefore accelerates directly to the chest of their team mate

Question 17

What happens is net force is positive?

Answer 17

acceleration

Question 18

What happens is net force is negative?

Answer 18

deceleration

Question 19

What is a balanced force?

Answer 19

Where two or more forces acting on a body and equal in size and opposite in direction. The net force will be 0, and the body will remain at rest or constant velocity

Question 20

What is an unbalanced force?

Answer 20

When two force and unequal in size and opposite in direction. A net fore will be present and the body will change its state of motion, either accelerating or decelerating