P1- Topic 1- Energy 2022

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

State two equations for power. Give SI

units for all quantities involved.

Answer 4

power = energy transferred/time

power = work done/time
Energy (J), Work Done (J), Time (s)

Question 5

What is the unit of power

Answer 5

Watt (W)

Question 6

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 6

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

Question 7

Describe the energy changes involved when a ball is thrown upwards and then returns to its starting position. Ignore air resistance 3

Answer 7

● Upwards: KE is converted to GPE

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

Question 8

Describe the energy transfers for a bungee jumper. 3

Answer 8

-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 9

Explain why a bungee jumper slows down once the

cord begins to stretch

Answer 9

● 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 10

Give examples of chemical energy stores

Answer 10

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

Question 11

State 4 different stores of energy

Answer 11

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

Question 12

State the law of energy conservation

Answer 12

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

Question 13

State any changes in the total energy of a ball that

is kicked, assuming that no external forces act

Answer 13

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

Question 14

What is waste energy?

Answer 14

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

sound energy in a motor

Question 15

Describe the energy changes that occur in a filament light-bulb.
3

Answer 15

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

Question 16

State two equations to calculate efficiency.

Answer 16

=Useful Output Energy Transfer/Total Input Energy Transfer
=Useful Power Output/Total Power
Output

Question 17

How can the efficiency of a system be increased? 2 with examples

Answer 17

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

Question 18

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

Answer 18

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

Question 19

Do double-glazed windows have a higher or lower

thermal conductivity than single-glazed windows?

Answer 19

Lower, meaning less energy transfers through them

Question 20

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

2

Answer 20

The thickness of the walls

● The thermal conductivity of the walls

Question 21

State three methods of reducing heat loss in a building

Answer 21

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

Question 22

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

Answer 22

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

Question 23

How can the efficiency of a radiator be improved?

Answer 23

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

Question 24

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

Answer 24

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

Question 25

What are the advantages of generating power using

gas rather than coal?

Answer 25

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

Question 26

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

Answer 26

● 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 27

Give an example of a social factor which may act as

a deterrent for certain types of energy production

Answer 27

● Visual Pollution

● Sound Pollution