Work, Energy And Momentum

Question 1

What is the unit of both work and energy?

Answer 1

Joule, J

Question 2

What is the energy transferred equal to?

Answer 2

Work done

Question 3

What is work done to overcome friction transferred as?

Answer 3

Energy that heats the objects that rub together and the surroundings

Question 4

What doe the gravitational potential energy of an object depend on?

Answer 4

It depends on its weight and how far it moves vertically

Question 5

What is gravitational potential energy?

Answer 5

Energy stored in an object because of its position in the earths gravitational field.

Question 6

What happens in terms of gravitational potential energy when an object is moved vertically?

Answer 6

It gains gravitational potential energy equal to the work done on it by the lifting force

Question 7

What is the change in gravitational potential energy measured in?

Answer 7

Joules

Question 8

What is gravitational field strength measured in?

Answer 8

N/kg

Question 9

What is power?

Answer 9

The rate of transfer of energy

Question 10

What does the kinetic energy of an object depend on?

Answer 10

Depends on the mass and speed of the object

Question 11

The greater the mass and the faster the speed of an object…

Answer 11

The more kinetic energy it has

Question 12

If an elastic band is stretched and then released what energy transfer occurs?

Answer 12

Elastic potential to kinetic energy

Question 13

What do all moving objects have?

Answer 13

Momentum

Question 14

What factors affect momentum?

Answer 14

Velocity
Mass
The greater each of them are the greater the momentum

Question 15

What is the unit of momentum?

Answer 15

Kgm/s also writes an Ns

Question 16

Whenever objects interact, the total momentum before the interaction is…

Answer 16

Equal to the momentum afterwards, provided no external forces act on them

Question 17

What happens in terms of momentum when objects interact provided no external forces act on them?

Answer 17

Momentum is conserved or the overall change in momentum is zero

Question 18

What does momentum have?

Answer 18

Size and direction

Question 19

When two objects are at rest what is their momentum?

Answer 19

Zero

Question 20

In an explosion what do the objects do to each other in terms of momentum?

Answer 20

They move apart with equal and opposite momentum, one momentum is positive and one is negative so the total momentum after the explosion is zero

Question 21

What happens when a force acts on an object that is able to move or is moving?

Answer 21

It changes momentum

Question 22

When vehicles collide what does the force of impact depend on?

Answer 22

Mass
Change in velocity
Duration of the impact

Question 23

For a particular change in momentum the longer the time taken for the change…

Answer 23

The smaller the force that acts

Question 24

In a collision the momentum of an object…

Answer 24

Often becomes zero during the impact- the object comes to rest

Question 25

If the impact time is short...

Answer 25

The forces on the object are large, as the impact time increases the forces become less

Question 26

What are crumple zones?

Answer 26

They are in cars and are designed to fold in a collision. This increases the impact time and so reduces the force on the car and the people in it

Question 27

What is impact time?

Answer 27

Time taken for a collision to take place

Question 28

What is the total momentum after an explosion equal to?

Answer 28

The total momentum before the explosion

Question 29

Two student on roller skates stand holding each other in the playground they push each other away. What can you say about the momentum of each student?

Answer 29

It is equal and opposite

Question 30

Why do cars have crumple zones at both the front and rear of the car?

Answer 30

The car could be hit from either the front or rear, in either case the crumple Zones reduce the forces on the car and increase impact time

Question 31

Crumple zones and side impact bars reduce the forces acting by...

Answer 31

Increasing the time taken to change the momentum of the car

Question 32

How do air bags reduce the forces on the occupants of the car in a collision?

Answer 32

They sleep read the forces across the body, if a drivers heads hits an airbag it changes momentum slowly so the forces on the head are less than it would be if it changed momentum quickly by hitting the steering wheel

Question 33

How do seat belts reduce the forces on the occupants of the car in a collision?

Answer 33

They stop the wearer being flung forward if the car stops suddenly, the seat belt stretches slightly increasing impact time and reducing the force

Question 34

When a force moves an object move what is done?

Answer 34

Energy is transferred and work is done

Question 35

What is work done to overcome friction transferred as?

Answer 35

Heat that is transferred to the surroundings