Speed, forces, velocity, ernergy to move, workdone

Question 1

What does a distance time graph show?

Answer 1

The distance an object moves in a period of time

Question 2

What is velocity?

Answer 2

An objects speed in a given direction.

Question 3

What is a change in velocity called?

Answer 3

Acceleration

Question 4

How do you work out the change in velocity?

Answer 4

Final velocity-original velocity

Question 5

What does a negative acceleration mean?

Answer 5

The object slows down

Question 6

What does a velocity time graph show?

Answer 6

How an objects velocity changes with time

Question 7

What is the resultant force of an object?

Answer 7

The single force that would make an object move as all the original forces acting together.

Question 8

What does it mean if there is no resultant force?

Answer 8

Forces are balanced and an object doesnt change speed. It is stationary

Question 9

In a vehicle, …… Consumption increases if drag force increase at a certain speed. A larger forward force is needed to overcome drag forces. More energy is needed from the engine to provide a larger forward force and keep going at the same speed.

Answer 9

Fuel

Question 10

What do streamlined objects have?

Answer 10

Small, cross sectional areas and smooth areas. This reduces drag forces so the objects can move faster for the same forward force.

Question 11

Why does a person feel heavier in a lift than normal?

Answer 11

Because when a lift accelerates upwards, the force from the floor pushing upwards is greater than the weight of the person in the lift.

Question 12

What is total stopping distance?

Answer 12

Thinking distance+ breaking distance

Question 13

What is reaction time?

Answer 13

The time taken for a driver to react to a hazard

Question 14

What can increase the thinking distance?

Answer 14

• if the driver is tired or distracted

- if the driver has drunk alcohol or taken drugs

Question 15

What can increase the braking distance?

Answer 15

• if the road is wet or icy
• the tyres are worn down
• the brakes are in bad condition
• the road surface

Question 16

What is aquaplanning?

Answer 16

Water from the surface of a wet road is channelled out through the treads of a tyre. If the tyre tread is worn down, water cannot be removed, so the car slides over a layer of water on the road and cannot be controlled. This is called aquaplanning.

Question 17

What is extension?

Answer 17

The difference between the original length and the stretched length.

Question 18

When an elastic object like a rubber band or spring is stretched:

• the extension is …….. To the force applied up to a limit.
• above the limit, extension is not propertional to the force.

Answer 18

Propertional

Question 19

What are work done and energy transfer measured in?

Answer 19

Joules

Question 20

What is power a measure of?

Answer 20

How quickly work is being done and how quickly energy is being transferred.

Question 21

What does the amount of gravitational potential energy depend on?

Answer 21

• mass

- height above ground

Question 22

All moving objects have kinetic energy. What does the amount of kinetic energy depend on?

Answer 22

• mass

- speed

Question 23

How much work is done when lifting a 250N box by 2m?

Answer 23

500J

Question 24

What force is needed to do a 500J of work over a distance of 5m?

Answer 24

100N

Question 25

What is the power of a machine that does 2000J of work in 5 seconds?

Answer 25

400W

Question 26

How much GPE does a rollercoaster car of mass 1000kg lose when it drops 5m?

Answer 26

1000x10x5=50,000J

Question 27

At the bottom of its swing, a pendulum has ..... GPE and ..... Kinetic energy?

Answer 27

Maximum GPE and minimum kinetic energy

Question 28

A car has more kinetic energy when ....

Answer 28

It is driven faster

Question 29

What is the kinetic energy of a 1000kg car driven at 13 m/s?

Answer 29

1/2 x 1000 x 13 x 13 =84,500J

Question 30

What is the unit of force?

Answer 30

The newton (N)

Question 31

What happens to a moving object if the resultant force is zero?

Answer 31

It keeps moving

Question 32

What happens to a moving object if the resultant force is not zero?

Answer 32

It speeds up in the direction of the resultant force.

Question 33

If you double the resultant force applied to an object, what happens to its acceleration?

Answer 33

It doubles

Question 34

What force is needed to give an acceleration of 2 m/s(squared) to a 4kg box?

Answer 34

8N

Question 35

What is terminal velocity?

Answer 35

When there is no resultant force and the object reaches a steady speed, called the terminal velocity.

Question 36

What is mass a measure of?

Answer 36

How much stuff is in an object.

Question 37

Elastic objects can store elastic potential energy when they are?

Answer 37

Stretched or squashed

Question 38

When an elastic object is changed from its original shape: work is .......?

Answer 38

Done

Question 39

Until a certain limit is reached, Hookes law states that: the extension of an elastic object is ....... .......... To the force applied?

Answer 39

Directly propertional

Question 40

A spring with k= 10N/m is stretched from 0.2 to 0.5m. The force needed is?

Answer 40

3N