Copy each passage into your book and fill in the numbered gaps using the word bank. Then check your answers. ← All topics
1. Energy stores and transfers (C+S)
When a system changes, energy is transferred between energy (1)______. The eight stores are kinetic, gravitational (2)______, elastic potential, (3)______, chemical, magnetic, electrostatic and nuclear. Energy can be transferred by a force doing (4)______, (5)______ (when a current flows), by heating, or by radiation. In a (6)______ system, there is no net change to the total energy.
Word bank: closed · electrically · potential · stores · thermal · work
Check your answers
1 stores · 2 potential · 3 thermal · 4 work · 5 electrically · 6 closed
2. Kinetic, gravitational and elastic energy (C+S)
A moving object has energy in its kinetic store: Ek = ½mv². Because speed is (1)______, doubling the speed makes the kinetic energy (2)______ times bigger. Raising an object increases its gravitational potential energy: Ep = mgh, where g is the gravitational field (3)______ (9.8 N/kg on Earth). A stretched spring stores elastic potential energy: Ee = ½ke², as long as the limit of (4)______ is not exceeded. The extension must be in (5)______ and the mass in (6)______.
Word bank: four · kilograms · metres · proportionality · squared · strength
Check your answers
1 squared · 2 four · 3 strength · 4 proportionality · 5 metres · 6 kilograms
3. Specific heat capacity (C+S)
The specific heat capacity of a substance is the energy needed to raise the temperature of (1)______ of it by (2)______. It is used in the equation ΔE = mcΔθ, where Δθ is the (3)______ in temperature. Water has a very (4)______ specific heat capacity (4200 J/kg °C). In the required practical, the energy supplied is found from a joulemeter or from power × (5)______, and the block is wrapped in (6)______ to reduce energy transferred to the surroundings.
Word bank: 1 °C · 1 kg · change · high · insulation · time
Check your answers
1 1 kg · 2 1 °C · 3 change · 4 high · 5 time · 6 insulation
4. Power (C+S)
Power is the (1)______ at which energy is transferred, or the rate at which (2)______ is done. It is measured in (3)______ (W); 1 W is a transfer of 1 (4)______ per second. If two motors lift the same load to the same height, the more powerful motor does it in (5)______ time.
Word bank: joule · less · rate · watts · work
Check your answers
1 rate · 2 work · 3 watts · 4 joule · 5 less
5. Conservation and dissipation of energy (C+S)
Energy can be transferred usefully, stored or dissipated, but it cannot be (1)______ or destroyed. Energy that is not transferred usefully is (2)______; it usually spreads out and heats the (3)______. Unwanted energy transfers can be reduced by (4)______ (to reduce friction) and by thermal (5)______. A building cools more slowly if its walls are (6)______ and have a lower thermal (7)______.
Word bank: conductivity · created · insulation · lubrication · surroundings · thicker · wasted
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1 created · 2 wasted · 3 surroundings · 4 lubrication · 5 insulation · 6 thicker · 7 conductivity
6. Efficiency (C+S)
Efficiency = (1)______ output energy transfer ÷ (2)______ input energy transfer. It can also be calculated using (3)______ instead of energy. Efficiency has no unit and can never be more than (4)______ (100%), because some energy is always (5)______.
Word bank: 1 · power · total · useful · wasted
Check your answers
1 useful · 2 total · 3 power · 4 1 · 5 wasted
7. Energy resources (C+S)
A (1)______ resource is one that is being (or can be) replenished as it is used, such as wind, solar, hydro-electricity, tides, water waves, geothermal and (2)______. Fossil fuels (coal, oil and gas) and nuclear fuel are (3)______ – they will run out. Fossil fuels are (4)______, but burning them releases carbon dioxide, which contributes to (5)______ change, and sulfur dioxide, which causes acid (6)______. Wind and solar are not reliable because they depend on the (7)______.
Word bank: bio-fuel · climate · non-renewable · rain · reliable · renewable · weather
Check your answers
1 renewable · 2 bio-fuel · 3 non-renewable · 4 reliable · 5 climate · 6 rain · 7 weather
