P2.3

Question 1

What causes the transfer of energy?

Answer 1

The work you do when working out.

Question 2

What does the work done by a force depend on?

Answer 2

On the size of the fore and distance moved.

Question 3

What is the equation for the work done?

Answer 3

=force applied(N) X distance moved in the direction of the force(m)

Question 4

What is gravitational potential energy?

Answer 4

Energy stored in an object because of its position in the Earth’s gravitational field.

Question 5

What happens to the gravitational potential energy when the object is moved up?

Answer 5

Increases.

Question 6

What happens to the gravitational potential energy when an object moves down?

Answer 6

Decreases.

Question 7

What is the equation for the change of potential energy?

Answer 7

=its weight(N) X change of height

Question 8

Why must energy be supplied to the muscles?

Answer 8

To keep the muscles contracted.

Question 9

What is the equation for the change in gravitational potential energy and mass?

Answer 9

=mass(kg) X gravitational field strength(N/kg) X change of height

Question 10

What is power?

Answer 10

Rate of transfer of energy.

Question 11

What is the equation for power?

Answer 11

P=E/t

Question 12

What is the equation for kinetic energy?

Answer 12

=1/2 X mass(kg) X speed2(m/s)2

Question 13

What does the kinetic energy recovery system do?

Answer 13

Stores energy in vehicles for when the vehicle brakes and uses it later.

Question 14

When stretching a rubber band c what is the work done stored in it as?

Answer 14

Elastic potential energy.

Question 15

What is elastic potential energy?

Answer 15

The energy stored in an elastic object when work is done on it to change its shape.

Question 16

Who is momentum important to?

Answer 16

Anyone who plays contact sport.

Question 17

What is the equation for the momentum of a moving object?

Answer 17

Momentum(kg m/s)=mass(kg) X velocity(m/s)

Question 18

What does the law of conservation of momentum state?

Answer 18

The total momentum before an event is equal to the total momentum after the event.

Question 19

In a front-end impact what happens to the momentum?

Answer 19

It’s reduced.

Question 20

In a rear-end impact what happens to the momentum?

Answer 20

It’s increased.

Question 21

Why does making the impact time longer reduce the impact force?

Answer 21

Momentum of the trolley would be lost over a longer time and it’s kinetic energy would be transferred over a greater distance.

Question 22

What is the equation for the impact force?

Answer 22

=mass(kg) X deceleration

Question 23

What happens when two vehicles collide?

Answer 23

They exert equal and opposite impact forces on each other at the same time.

Question 24

What happens to the change of momentum when two vehicles collide?

Answer 24

The change of momentum is equal and opposite to the change of momentum of the other vehicle.

Question 25

Why do seat belts reduce the force on people in car accidents?

Answer 25

Stops its wearer from continuing forwards when the car stops.

Question 26

Why do air bags reduce the force on people in car accidents?

Answer 26

It spreads the force of an impact across the upper part of the body.

Question 27

Why are ordinary car seat belts unsafe for children?

Answer 27

Because the seat belt won’t fully support them because it won’t fit around their whole body.

Question 28

Name safety features in a car:

Answer 28

• front and rear seat belts
• airbags
• frogs and rear crumple zone
• side impact bars