Energy

Question 1

What does the principle of conservation of energy say

Answer 1

Energy cannot be created or destroyed. It can only be transferred from one store of energy into another.

Question 2

When an object is projected upwards, what store is its energy in at its highest point?

Answer 2

Gravitational potential

Question 3

What energy transfers are involved in a vehicle slowing down

Answer 3

To begin with the vehicle has its energy in the KINETIC STORE.
It then gets transferred to the THERMAL STORE by the brakes
We say the the brakes DO WORK on the car.

Question 4

What are the 4 methods of energy transfer

Answer 4

Electrical work
Waves
Heat
Mechanical work

Question 5

Work done =

Answer 5

Force x distance (moved along the line of action of the force)

Question 6

Efficiency (power in watts) =

Answer 6

useful power output/total power input (W) x 100

Question 7

Efficiency (energy in joules) =

Answer 7

useful energy output/total energy input (J)x 100

Question 8

What are the advantages of geothermal energy

Answer 8

Renewable
Reliable

Question 9

What are the disadvantages of geothermal energy

Answer 9

Can only be used where there is volcanic activity close to the surface

Question 10

What are the advantages of hydroelectric power

Answer 10

Renewable.
More reliable than wind and solar.

Question 11

What are the disadvantages of hydroelectric power

Answer 11

Hydroelectric dams often change the paths of rivers, which can move people out of houses and harm local wildlife.

Question 12

What are the advantages of tidal energy

Answer 12

Renewable

Question 13

What are disadvantages of tidal energy

Answer 13

The creation of tidal turbines can damage fragile ecosystems in estuaries.

Question 14

What are the disadvantages of nuclear energy

Answer 14

Disposal of nuclear waste with very long half-life can cause serious safety issues.
Widespread and long term damage if an accident occurs.

Question 15

What are the advantages of nuclear energy

Answer 15

No greenhouse gas emission, so no contribution to global warming.
Reliable, on-demand electricity.

Question 16

What are the advantages of solar energy

Answer 16

Renewable

Question 17

What are the disadvantages of solar energy

Answer 17

Only produces electricity when there is sunlight.

Question 18

What are 3 problems with renewable energy resources

Answer 18

Politics can interfere
They cost more
They are less reliable

Question 19

Change in gravitational GPE =

Answer 19

mass x gravity x change in height

Question 20

KE=

Answer 20

1/2 x mass x velocity squared

Question 21

How is energy stored when a system changes : a pirate ship ride at a theme park

Answer 21

At the highest point of the swing:
No kinetic energy
Maximum GPE

Question 22

How is energy stored when a system changes :boiling a kettle

Answer 22

Electrical current increases the thermal energy of the element which in turn increases the internal energy of the water which increases the temperature of the water

Question 23

How is energy stored when a system changes : a boat being accelerated by the force of an engine

Answer 23

The boat pushes through the water as chemical energy is transferred into kinetic energy
Loses chemical energy as fuel is burnt
Gains kinetic energy as it gains speed

Question 24

How is energy stored when a system changes : a car breaking in an emergency

Answer 24

kinetic energy is transferred into thermal energy of the surroundings by the work done by the force of friction on the brakes

Question 25

What are the three different ways that energy of a system can be changed

Answer 25

Through work done by forces
in electrical equipment
in heating

Question 26

When do mechanical processes become wasteful

Answer 26

When they cause a rise in temperature so dissipating energy in heating the surroundings

Question 27

Power =

Answer 27

Work done (Energy) divided by time taken