Energy

Question 1

Name the 8 energy stores.

Answer 1

Thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic, nuclear.

Question 2

What is a system in physics?

Answer 2

An object or group of objects considered for energy transfer analysis.

Question 3

What happens to energy in a closed system?

Answer 3

The total energy remains constant, but it can be transferred between stores.

Question 4

What is the equation for kinetic energy?

Answer 4

KE = 0.5 × mass × velocity²

Question 5

What is the equation for gravitational potential energy?

Answer 5

GPE = mass × gravitational field strength × height

Question 6

What affects the amount of kinetic energy?

Answer 6

Mass and velocity of the object.

Question 7

When is GPE highest?

Answer 7

When an object is at its highest point above the ground.

Question 8

What is the equation for elastic potential energy?

Answer 8

EPE = 0.5 × spring constant × extension²

Question 9

What does the spring constant represent?

Answer 9

Stiffness of the spring; measured in N/m.

Question 10

What does ‘extension’ mean in EPE calculations?

Answer 10

How much the spring is stretched beyond its original length.

Question 11

What is specific heat capacity?

Answer 11

The amount of energy needed to raise the temperature of 1 kg of a substance by 1°C.

Question 12

What is the equation for energy change using specific heat capacity?

Answer 12

ΔE = mass × specific heat capacity × temperature change

Question 13

What is power?

Answer 13

The rate of energy transfer or work done.

Question 14

What is the equation for power?

Answer 14

Power = Energy transferred ÷ time or Power = Work done ÷ time

Question 15

What is the unit of power?

Answer 15

Watt (W)

Question 16

What is efficiency?

Answer 16

The ratio of useful output energy to total input energy.

Question 17

How can efficiency be calculated?

Answer 17

Efficiency = (useful energy output ÷ total energy input) × 100

Question 18

Can any device be 100% efficient?

Answer 18

No, some energy is always wasted, usually as heat.

Question 19

Name three renewable energy resources.

Answer 19

Solar, wind, hydroelectric.

Question 20

Name three non-renewable energy resources.

Answer 20

Coal, oil, natural gas.

Question 21

What are the advantages of renewable energy?

Answer 21

Won’t run out, less pollution.

Question 22

What are disadvantages of renewable energy?

Answer 22

Weather dependent, expensive setup.

Question 23

What are the environmental issues with fossil fuels?

Answer 23

They release CO₂ and other pollutants when burned.

Question 24

What is base load electricity?

Answer 24

The constant supply of electricity required, often provided by nuclear or fossil fuels.

Question 25

Name 4 ways energy can be transferred.

Answer 25

Mechanically, electrically, by heating, or by radiation.

Question 26

What is dissipation of energy?

Answer 26

The spreading out and loss of energy, usually as heat.

Question 27

How can energy loss through heating be reduced?

Answer 27

Insulation, double glazing, cavity wall insulation.

Question 28

How can friction be reduced?

Answer 28

Using lubricants like oil to reduce contact between surfaces.

Question 29

Is energy 'used up' during a process?

Answer 29

No, energy is transferred or dissipated, but not destroyed.

Question 30

Does a high power rating always mean better efficiency?

Answer 30

No, it means faster energy transfer, not necessarily less waste.

Question 31

Can an object at rest have energy?

Answer 31

Yes, it may have potential energy.

Question 32

Is heat the same as temperature?

Answer 32

No, heat is energy; temperature is a measure of how hot something is.

Question 33

Does more mass always mean more kinetic energy?

Answer 33

Not necessarily—velocity also matters (KE = 0.5mv²).

Question 34

Does all input energy become useful energy?

Answer 34

No, some is always wasted, often as heat or sound.

Question 35

Does renewable mean unlimited power output?

Answer 35

No, it depends on environmental conditions like sunlight or wind.

Question 36

What does a steeper gradient on a temperature-time graph mean?

Answer 36

Greater rate of temperature change (lower SHC).

Question 37

What does a flat section on a heating curve represent?

Answer 37

A change of state; temperature remains constant.

Question 38

How can you identify SHC from a graph?

Answer 38

Use the gradient of the linear section after heating starts.

Question 39

What does the area under a force-extension graph represent?

Answer 39

Elastic potential energy stored.

Question 40

What happens to temperature during a change of state?

Answer 40

It stays constant while energy is used to break bonds.

Question 41

What does a linear increase on a KE vs velocity² graph show?

Answer 41

That KE is directly proportional to velocity squared.

Question 42

What equation uses: mass, gravitational field strength, and height?

Answer 42

Gravitational potential energy: GPE = m × g × h

Question 43

What equation uses: 0.5 × mass × velocity²?

Answer 43

Kinetic energy

Question 44

Which formula do you use to calculate energy in a spring?

Answer 44

EPE = 0.5 × k × e²

Question 45

Which variable would you increase to reduce SHC energy transfer time?

Answer 45

Use a substance with lower specific heat capacity.

Question 46

If you double the velocity, what happens to KE?

Answer 46

It quadruples (KE ∝ velocity²).

Question 47

If an appliance uses 600 J in 2 seconds, what is its power?

Answer 47

300 W (Power = Energy ÷ Time)

Question 48

If a kettle is 80% efficient and transfers 800 J usefully, what was the total input energy?

Answer 48

1000 J (800 ÷ 0.8)