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Flashcards in P1: Energy Deck (24)
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1
Q

What are the types of energy store?

A

-Thermal -Kinetic -Gravitational -Elastic potential -Chemical -Magnetic -Electrostatic -Nuclear

2
Q

What are the types of energy transfer?

A

-Mechanically (by a force doing work) -Electrically (work done by moving charges) -By heating -By radiation (through the EM spectrum, e.g. light or UV radiation) Overall, energy can be transferred by heating or by doing work.

3
Q

What is the equation for kinetic energy?

A

Kinetic energy (J) = ½ x mass (kg) x velocity2 (m/s) Ek = ½ mv2

4
Q

What is the equation for gravitational potential energy?

A

Gravitational potential energy (J) = mass (kg) x gravitational field strength (N/kg) x height (m) Ep = mgh

5
Q

What is the law of conservation of energy?

A

Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.

6
Q

What is power and what is it measured in?

A

Power is the rate of energy transfer / work done, measured in watts (W).

7
Q

What are the two equations for power?

A

1) Power (W) = energy transferred (J) ÷ time (s) P = E/t 2) Power = work done (J) ÷ time (s) P = W/t

8
Q

What causes energy to be wasted?

A

Resistance and friction

9
Q

In what two ways can heating occur?

A

1) Conduction (solids) 2) Convection (liquid & gases)

10
Q

What is specific heat capacity?

A

The amount of energy required to raise the temperature of 1 kg of a substance by 1ºC.

11
Q

The formula for specific heat capacity is given (ΔE = mcΔθ). What is its symbol and unit?

A

Symbol: c

Unit: J / kg°C

12
Q

Describe how you would find the specific heat capacity of a solid block of a material.

A
  • You’ll need a solid block of the material, with 2 holes for the heater and thermometer to go into.
  • Measure the block’s mass using a balance.
  • Wrap it in an insulating layer (decreases energy dissipated from block to surroundings).
  • Connect a heater to a power supply and ammeter, and place it into one of the object’s holes.
  • Place a thermometer into the other and measure the initial temperature of the block.
  • Set the power supply at 10V, then turn it on and immediately start a stopwatch.
  • The current transfers energy to the heater’s thermal energy store, which is then transferred to the object’s.
  • The ammeter reading should remain constant.
  • Measure the temperature on the thermometer every 30 seconds. Turn off the power when you have 10 readings.
  • Find the energy transferred to the heater at each reading using the formula E = VIt (bc E = Pt and P = VI).
  • Assuming all the energy transferred to the heater was transferred to the block, find the SHC using the rearrangement c = ΔE/mΔθ.
  • The plotted relationship between energy transferred and temperature would be directly proportional.
13
Q

Describe how you could investigate the effectiveness of different insulators.

A
  • Boil water in a kettle and use a balance to pour a set mass into a beaker.
  • Use a thermometer to measure the initial temperature.
  • Seal the beaker with a lid and use a stopwatch to leave it for 5 minutes.
  • Remove the lid and measure the water’s final temperature.
  • Pour away the water; allow the beaker to cool to room temperature.
  • Repeat steps 1-4 (use same mass of water each time!), wrapping the beaker in a different material (foil, newspaper, bubble wrap) each time.
  • The most effective insulator is that which reduces the temperature difference by the largest degree.

<em>This investigation could be modified to instead test how the thickness of an insulator affects heat loss.</em>

14
Q

What are non-renewable energy resources?

A

Non-renewable energy resources are ones that cannot be replenished as they are used up. They usually do damage to the environment.

15
Q

Specifically what are non-renewable energy resources?

A

Nuclear

Fossil fuels

16
Q

Non-renewables provide most of our energy. Why?

A

They are reliable. There is enough fuel to meet current demand, and they are extracted at a fast enough rate that power plants always have fuel in stock, so they can respond quickly to changes in demand.

17
Q

What are the pros of fossil fuels?

A
  • Reliable.
  • Enough to meet current demand and respond to changes in demand.
  • Cost effective: while the setup costs of power plants are high, running and fuel extraction costs are fairly low.
18
Q

What are the cons of fossil fuels? Give at least three.

A
  • Finite/non-renewable.
  • They release CO2 into the atmosphere when burned, adding to the greenhouse effect and global warming.
  • Power plants ruin the view.
  • Burning coal and oil releases sulfur dioxide, causing acid rain. Reduced by taking sulfur out before combustion.
  • Coal mining, especially open cast, ruins the landscape.
  • Oil spillages cause serious environmental problems.
19
Q

What are the pros of nuclear power?

A
  • Reliable.
  • Enough to meet current demand.
  • Power plants can respond to changes in demand.
20
Q

What are the cons of nuclear power? Give at least three.

A
  • Finite/non-renewable
  • Power plants ruin the view.
  • Nuclear waste is dangerous and hard to dispose of.
  • Fuel is relatively cheap, but overall cost of nuclear power is high due to cost of power plants and final decommissioning.
  • Nuclear power carries the risk of a major catastrophe.
21
Q

What are renewable energy resources?

A

Natural energy sources that will never run out if we replenish them as they’re used. Most of them do damage to the environment, but less than non-renewables do.

22
Q

Why don’t renewables provide the majority of our energy?

A
  • They aren’t very efficient.
  • They are unreliable; they depend on the weather.
  • They often can’t respond to changes in demand.
23
Q

Where and how is geothermal energy sourced?

A

Geothermal power is harnessed from underground stores of thermal energy. The source of much of the energy is the decay of radioactive elements (e.g. uranium) deep inside the Earth.

24
Q

What are biofuels?

A

Fuels taken from [recently] living materials, e.g. plant products and animal waste. -They can be solid, liquid or gas. -They can be burnt to produce electricity, or run cars, in the same way as fossil fuels.