Chapter 2

Question 0

What is work done?

Answer 0

When a force moves an object through a distance and energy is transferred

Question 1

Energy can be transferred only usefully. True or False?

Answer 1

False-energy can also be transferred wastefully

Question 2

What are the units for work done and energy transferred?

Answer 2

Joules

Question 3

What is gravitational potential energy?

Answer 3

The energy an object has because of its vertical position in a gravitational field

Question 4

What happens when an object is raised vertically?

Answer 4

Work is done against the force of gravity and gravitational potential energy is gained

Question 5

What has kinetic energy?

Answer 5

Anything moving

Question 6

How is a car slowed down?

Answer 6

Kinetic energy needs to be converted into other types of energy-meaning work is done

Question 7

What do falling objects do?

Answer 7

Convert gravitational potential energy into kinetic energy.

Kinetic energy gained = Gravitational potential energy lost

Question 8

What happens to the energy when work is done to an elastic object?

Answer 8

It is stored as elastic potential energy

Question 9

What is the definition of an elastic object?

Answer 9

Anything that can return to its original shape after a force has been removed.

Question 10

What happens when the force is removed off an elastic object?

Answer 10

The elastic potential energy is converted into kinetic energy

Question 11

Extension is indirectly proportional to force. True or false?

Answer 11

False-extension is directly proportional to force.

Question 12

What is the limit of proportionality?

Answer 12

There is a maximum force that the elastic object can take and still extend proportionally.

Question 13

What is power?

Answer 13

The rate of work doing or energy transferred per second

Question 14

What is the unit of power?

Answer 14

Watts or Joules per second

Question 15

Momentum has size and direction so is a vector quantity. True or False?

Answer 15

True

Question 16

What is momentum dependent on?

Answer 16

Mass and velocity

Question 17

What is the conservation of momentum?

Answer 17

Momentum before = Momentum after

Question 18

When catching a ball, you bring the ball into your body, this affects the rate of change in momentum and so the force. How does it do this?

Answer 18

• It increases the time taken for the momentum to change,
• this decreases the rate of change in momentum
• which decreases the size of the impact force.

Question 19

What do regenerative breaks do?

Answer 19

They put the motor in reverse slowing the wheels down. They also convert the kinetic energy into electrical energy that is stored as chemical energy in the vehicles battery.

Question 20

What happens in a crash?

Answer 20

Kinetic energy is converted into other forms of energy in a short period of time. There is also a big change in momentum over a short space of time, meaning people experience huge forces

Question 21

What do crumple zones do?

Answer 21

They convert kinetic energy into other forms of energy as they change shape. They also increase the impact time, decreasing the force produced by the change in momentum.

Question 22

What do side impact bars do?

Answer 22

They direct the kinetic energy away from passengers to other areas of the car

Question 23

What do seat belts do?

Answer 23

They stretch, increasing the time taken for the passenger to stop. This reduces the forces acting on the chest and absorbs some of the kinetic energy

Question 24

What do air bags do?

Answer 24

They slow the passenger down and prevent them hitting hard surfaces.