Energy questions

By Interwoven Maths

Energy question collection

Review Energy questions for Physics, with correct answers shown and coverage across energy stores and transfers; conservation of energy; efficiency and power.

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Question 1

Which set contains only energy stores?
  1. Kinetic, thermal, gravitational potential
  2. Kinetic, heat, gravitational potential
  3. Chemical, electrical, thermal
  4. Elastic potential, sound, nuclear

Question 2

Which equation gives kinetic energy \(E_k\)?
  1. \(E_k = \tfrac{1}{2}mv^2\)
  2. \(E_k = mgh\)
  3. \(E_k = P t\)
  4. \(E_k = \tfrac{1}{2}k e^2\)

Question 3

If the speed of an object doubles and mass stays constant, what happens to its kinetic energy?
  1. Increases by a factor of \(4\)
  2. Increases by a factor of \(2\)
  3. Increases by a factor of \(8\)
  4. Stays the same

Question 4

Which equation links the change in thermal energy with mass, specific heat capacity and temperature change?
  1. \(\Delta E = mc\Delta \theta\)
  2. \(\Delta E = mL\)
  3. \(P = VI\)
  4. \(Q = It\)

Question 5

What is specific heat capacity?
  1. The energy needed to raise the temperature of \(1\,\mathrm{kg}\) of a substance by \(1\,^\circ\mathrm{C}\)
  2. The energy needed to melt \(1\,\mathrm{kg}\) of a substance at constant temperature
  3. The energy needed to increase the pressure of \(1\,\mathrm{m}^3\) of gas by \(1\,\mathrm{Pa}\)
  4. The energy needed to move \(1\,\mathrm{kg}\) at \(1\,\mathrm{m/s}\)

Question 6

Which equation defines power as the energy transferred per unit time?
  1. \(P = \frac{E}{t}\)
  2. \(P = Et\)
  3. \(P = \frac{V}{I}\)
  4. \(P = mgh\)

Question 7

A machine has \(200\,\mathrm{J}\) input and \(150\,\mathrm{J}\) useful output. What is its efficiency?
  1. \(75\%\)
  2. \(25\%\)
  3. \(133\%\)
  4. \(50\%\)

Question 8

How can unwanted energy transfer by heating from a hot pipe be reduced?
  1. Add thermal insulation around the pipe
  2. Increase the pipe temperature
  3. Use a thinner pipe wall
  4. Increase thermal conductivity

Question 9

Which equation gives energy transferred by electrical work using charge \(Q\) and potential difference \(V\)?
  1. \(E = QV\)
  2. \(E = IV\)
  3. \(E = \frac{Q}{I}\)
  4. \(E = \frac{V}{Q}\)

Question 10

In a closed system, dissipated energy is...
  1. Conserved but spread out
  2. Conserved in its original store
  3. Transferred outside the system
  4. Converted into useful work

Question 11

How many megajoules equal \(1\,\mathrm{kWh}\)?
  1. \(3.6\,\mathrm{MJ}\)
  2. \(0.0036\,\mathrm{MJ}\)
  3. \(3600\,\mathrm{MJ}\)
  4. \(1\,\mathrm{MJ}\)

Question 12

A \(1.5\,\mathrm{kW}\) kettle runs for \(4\,\mathrm{s}\). How much energy is transferred?
  1. \(6\,\mathrm{kJ}\)
  2. \(0.375\,\mathrm{kJ}\)
  3. \(5.5\,\mathrm{kJ}\)
  4. \(6000\,\mathrm{kJ}\)

Question 13

Charge of \(5\,\mathrm{C}\) passes through a potential difference of \(12\,\mathrm{V}\). How much energy is transferred?
  1. \(60\,\mathrm{J}\)
  2. \(0.42\,\mathrm{J}\)
  3. \(5\,\mathrm{J}\)
  4. \(60\,\mathrm{kJ}\)

Question 14

Which formula defines efficiency?
  1. \(\text{efficiency} = \frac{\text{useful energy output}}{\text{total energy input}}\)
  2. \(\text{efficiency} = \frac{\text{total input}}{\text{useful output}}\)
  3. \(\text{efficiency} = \text{power} \times \text{time}\)
  4. \(\text{efficiency} = \text{voltage} \times \text{current}\)

Question 15

Which expression gives elastic potential energy?
  1. \(\tfrac{1}{2}ke^2\)
  2. \(ke\)
  3. \(\tfrac{1}{2}mv^2\)
  4. \(mgh\)

Question 16

For fixed Grid power, which combination reduces cable heating?
  1. Higher voltage, lower current
  2. Lower voltage, higher current
  3. Higher voltage, higher current
  4. Lower voltage, lower current

Question 17

Which energy resource is renewable?
  1. Wind
  2. Oil
  3. Coal
  4. Natural gas

Question 18

Which conversion occurs in a photovoltaic panel?
  1. Light to electrical
  2. Thermal to electrical
  3. Electrical to light
  4. Chemical to electrical

Question 19

Which equation gives gravitational potential energy \(E_p\)?
  1. \(E_p = mgh\)
  2. \(E_p = \frac{mg}{h}\)
  3. \(E_p = mg + h\)
  4. \(E_p = m^2 g^2\)

Question 20

A \(150\,\mathrm{N}\) load rises \(4\,\mathrm{m}\). How much gravitational potential energy is gained?
  1. \(600\,\mathrm{J}\)
  2. \(37.5\,\mathrm{J}\)
  3. \(154\,\mathrm{J}\)
  4. \(6000\,\mathrm{J}\)

Question 21

A \(1\,\mathrm{kg}\) material with \(c=500\,\mathrm{J/(kg\,^{\circ}C)}\) warms by \(4\,^{\circ}C\). Energy gained?
  1. \(2000\,\mathrm{J}\)
  2. \(125\,\mathrm{J}\)
  3. \(504\,\mathrm{J}\)
  4. \(500\,\mathrm{J}\)

Question 22

How does lubrication reduce wasted energy in a machine?
  1. It reduces heating caused by friction
  2. It increases the machine's mass
  3. It raises the electrical resistance
  4. It stores more energy in gravity

Question 23

Why can wind power be less reliable than gas power?
  1. Its output depends on the weather
  2. Its fuel supply is finite
  3. Its output is constant
  4. Its generator produces direct current

Question 24

An audit records \(2000\,\mathrm{J}\) input and \(1800\,\mathrm{J}\) useful output. How much is wasted?
  1. \(200\,\mathrm{J}\)
  2. \(1800\,\mathrm{J}\)
  3. \(2000\,\mathrm{J}\)
  4. \(3800\,\mathrm{J}\)

Question 25

Which power rating transfers \(3000\,\mathrm{J}\) in \(10\,\mathrm{s}\)?
  1. \(300\,\mathrm{W}\)
  2. \(30\,\mathrm{W}\)
  3. \(3000\,\mathrm{W}\)
  4. \(0.3\,\mathrm{W}\)

Question 26

Which energy resource produces radioactive waste?
  1. Nuclear
  2. Wind
  3. Solar
  4. Tidal

Question 27

A \(2\,\mathrm{kg}\) object moves at \(3\,\mathrm{m/s}\). What is its kinetic energy?
  1. \(9\,\mathrm{J}\)
  2. \(6\,\mathrm{J}\)
  3. \(18\,\mathrm{J}\)
  4. \(4.5\,\mathrm{J}\)

Question 28

Which transfer lowers an electric motor's efficiency?
  1. Heating the surroundings
  2. Turning the output shaft
  3. Lifting the attached load
  4. Moving the vehicle

Question 29

Which station can begin supplying extra power fastest?
  1. Pumped storage
  2. Gas turbine
  3. Coal station
  4. Nuclear station

Question 30

During low demand, pumped storage increases which energy store?
  1. Gravitational potential
  2. Kinetic
  3. Chemical
  4. Thermal

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Review Energy questions for Physics, with correct answers shown and coverage across energy stores and transfers; conservation of energy; efficiency and power.

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