Unit 1 - Energy

Question 1

Define the ‘Specific Heat Capacity’ of a substance.

Answer 1

The amount of energy needed to raise
the temperature of 1 kilogram of a
substance by 1 degree Celsius.

Question 2

State the units for Specific Heat Capacity

Answer 2

J/°C/kg
Joules/Degree Celsius/Kilogram

Question 3

What is the definition of ‘Power’?

Answer 3

The rate at which energy is transferred
(or rate at which work is done).

Question 4

What is the unit of power?

Answer 4

Watt (W)

Question 5

Two motors lift the same mass through the same
height. Motor A does this in half the time of Motor B.
Which dissipates the most power?

Answer 5

Motor A.
The energy transferred is the same but
the time taken is less (P=E/t).

Question 6

Describe the energy changes involved when a ball is
thrown upwards and then returns to its starting
position. Ignore air resistance.

Answer 6

● Upwards: KE is converted to GPE
● Peak: Maximum GPE, zero KE
● Downwards: GPE is converted to KE

Question 7

Describe the energy transfers for a bungee jumper.

Answer 7

● When falling, the GPE is converted to KE of
jumper
● As the cord tightens, KE is converted and
stored as Elastic Potential Energy (EPE)
● At lowest point, the jumper’s initial GPE
equals the EPE stored in the cord

Question 8

Explain why a bungee jumper slows down once the
cord begins to stretch.

Answer 8

● Kinetic energy decreases since it is
converted to elastic potential energy
● Since KE is proportional to (velocity)²,
as KE decreases, so does velocity.

Question 9

Give examples of chemical energy stores.

Answer 9

● Food
● Fuel (eg. wood, coal, petrol)
● Batteries

Question 10

State 4 different stores of energy.

Answer 10

1. Kinetic Energy
2. Gravitational Potential Energy
3. Elastic Potential Energy
4. Chemical Energy

Question 11

State the law of energy conservation.

Answer 11

Energy cannot be created or destroyed
(it can only be transferred into different
forms).

Question 12

State any changes in the total energy of a ball that
is kicked, assuming that no external forces act.

Answer 12

The total energy of the system remains
constant due to the conservation of
energy.

Question 13

What is waste energy?

Answer 13

The energy that is not used by the device
for its desired purpose.

Question 14

Describe the energy changes that occur
in a filament light-bulb.

Answer 14

● Electrical energy is transferred into
light and heat energy
● Light is a useful energy form, heat is
waste energy

Question 15

How can the efficiency of a system be increased?

Answer 15

1. Reducing waste output (by
   lubrication, thermal insulation etc.)
2. Recycling waste output (eg. recycling
   thermal waste energy as input energy)

Question 16

State the consequence for energy transfer of a
material with a high thermal conductivity.

Answer 16

The rate of energy transfer through the
material is higher than for a material with
a lower thermal conductivity.

Question 17

Do double-glazed windows have a higher or lower
thermal conductivity than single-glazed windows?

Answer 17

Lower, meaning less energy transfers
through them.

Question 18

What key factors affect the rate of cooling of a
building?

Answer 18

● The thickness of the walls
● The thermal conductivity of the walls

Question 19

State three methods of reducing heat
loss in a building.

Answer 19

1. Double glazing
2. Loft and wall insulation
3. Thicker walls

Question 20

How can the efficiency of a mechanical machine with
moving parts be improved?

Answer 20

Lubricate any moving parts to reduce the
friction and therefore energy loss due to
heating.

Question 21

How can the efficiency of a radiator be improved?

Answer 21

Installing metal foil sheets behind the
radiator to reflect the heat back into the
room rather than it being absorbed into
the walls.

Question 22

How can the efficiency of boiling water in a pan be
improved?

Answer 22

By placing a lid on the pan to reduce the
heat loss from the top.

Question 23

What is a renewable energy resource?

Answer 23

An energy source which can be
replenished as it is being used up.

Question 24

Give four examples of renewable energy resources.

Answer 24

1. Wind Energy
2. Hydro-Electricity
3. Tidal Energy
4. Solar Energy

Question 25

Give an example of a non-renewable energy
resource.

Answer 25

Fossil fuels (for example coal, oil and
gas).

Question 26

What are the advantages of generating power using
gas rather than coal?

Answer 26

● Flexible Generation: Gas power
stations have short start-up times so
can be switched on/off more readily
● Lower emissions of carbon dioxide

Question 27

State two disadvantages of using renewable energy
resources to generate power.

Answer 27

● Output often determined by external factors
(like wind speed), so supply is uncertain
● Generating power through other means is
often more efficient and economically
beneficial

Question 28

Explain the environmental impacts of burning fossil
fuels.

Answer 28

● Carbon Dioxide contributes to the
greenhouse effect, and causes global
warming
● Sulphur Dioxide leads to acid rain, which
can damage buildings and crops

Question 29

State three advantages of fossil fuels as an energy
resource.

Answer 29

1. Reliable: Not dependent on external factors
   so can generate power anytime
2. Can produce large amounts of energy for a
   given quantity
3. Still relatively abundant, so cost-effective

Question 30

State three advantages of nuclear power.

Answer 30

1. Very large amounts of energy for relatively
   small quantities of fuel
2. Doesn’t release greenhouse gases and so
   doesn’t contribute to climate change
3. Low fuel costs

Question 31

State three disadvantages of nuclear power.

Answer 31

1. Produces nuclear waste which is harmful to
   humans & must be safely stored for centuries.
2. Non-Renewable energy source
3. Risk of nuclear accidents, which have fatal
   consequences on humans and the
   environment

Question 32

How does hydroelectric power produce energy?

Answer 32

● Rainwater collects behind a dam
● When this water is released, it is used
to turn a turbine
● This turbine turns a generator which
produces electricity

Question 33

What are some disadvantages of using biofuels?

Answer 33

● When plants are burned or decay they release CO2
● In order to grow biofuels, you need to destroy land
which leads to problems because:
○ The land could have been natural habitats
○ Destroying land may involve burning plants growing
on it, which would release CO2
● Growing biofuels reduces the land available for growing
food

Question 34

What are the advantages of tidal energy sources?

Answer 34

● They do not produce greenhouse gases
● They are quite reliable, as tides happen
twice a day
● They are cheap to run as tides are
natural, and so are free

Question 35

What are the disadvantages of hydroelectric power?

Answer 35

● The dam may cause flooding
● It can cost a lot to install the required
infrastructure

Question 36

What are some advantages of solar panels?

Answer 36

● They don’t cause harm to the
environment
● They are a renewable resource
● They can be used in remote areas where
other types of energy are less accessible

Question 37

Give an example of a social factor which may act as
a deterrent for certain types of energy production.

Answer 37

● Visual Pollution
● Sound Pollution