Energy Stores

Question 1

What are the 4 ways energy can be transfered?

Answer 1

Mechanically - when force does work on a object.
By heating - when energy is transferred from a hotter object to a cooler object.
Electrically - when a moving charge does work.
Radiation - when energy is transferred by e.g sound or light.

Question 2

What are closed systems?

Answer 2

Systems where no matter (stuff) or energy can enter or leave.
(when a closed system changes, there is no net (overall) change in the total energy of the system.)

Question 3

Energy can…

Answer 3

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

Question 4

If a force moves an object what is being done?

Answer 4

Work is done.

Question 5

What is the formula for finding the energy in an objects kinetic energy?

Answer 5

Kinetic energy = 1/2 mv^2

Question 6

What energy store is anything that moves?

Answer 6

Kinetic energy.

1. Energy is transferred to the kinetic energy store when an object speed up.
2. Energy is transferred away from this store when a object slows down.

Question 7

What energy store is raised objects?

Answer 7

Gravitational potential energy store.

1. All objects raised above the ground gain energy in there gravitational potential energy store.

Question 8

What is the formula for finding the energy in an objects g.p.e store?

Answer 8

G.p.e. = mgh

(Gravitational potential energy = mass x gravitational field strength x height.)

Question 9

What energy store is stretching?

Answer 9

Elastic potential energy store.
1. Stretching or squashing and object can transfer energy to its elastic potential energy store.

Question 10

Whats the formula for finding the elastic potential energy store of a stretched object?

Answer 10

E= 1/2 ke

(Elastic potential energy = 1/2 x spring constant x extension x2.)

Question 11

what energy store can be transferred by heating?

Answer 11

Thermal energy store.

1. As a material is heated, energy gets transferred to the thermal energy store.
2. This causes temperature to increase.

Question 12

What’s the formula for specific heat capacity?

Answer 12

Change in thermal energy = mass x specific heat capacity x temperature change.

Question 13

What’s specific heat capacity?

Answer 13

The amount of energy needed to raise the temperature of 1kg of a material by 1 degree Celsius

Question 14

What’s the practice for specific heat capacity?

Question 15

What’s the formula to calculate power?

Answer 15

P = e / t

Power = energy transferred / time

Question 16

What are ways you can reduce the amount of energy wasted?

Answer 16

1.Lubrication reduces frictional forces
2.insulation has a low thermal conductivity
3. Insulation is important for keeping buildings warm

Question 17

How does lubrication reduce energy loss?

Answer 17

1.friction adds between all object that run together.
2. This causes some energy in the system to be dissipated.

Question 18

How does insulation reduce energy loss?

Answer 18

1. When a part of a material is heated, that part of the material gains energy.
2. This energy is transferred across the material so that the rest I’d the material gets warmer.
3. This is known as conduction.
4. Thermal conductivity is a measure of how quickly energy is transferred by conduction throw a material.
5. Materials with high thermal conductivity transfer lots of energy in a short time
6. Materials with low thermal conductivity are called thermal insulators.
7. Thermal insulators can reduce unwanted transfers by heating,

Question 19

fill blanks (…) :
The …. energy wasted, the …. efficient the energy transfer is.

Answer 19

The less energy transferred, the more efficient the energy transfer is.

Question 20

What are the 6 renewable resources?

Answer 20

1. The sun (solar)
2. Wind
3. Water waves
4. hydro-electricity
5. bio-fuels
6. tides
7. geothermal

Question 21

Describe wind turbines effects on the environment and how they work.

Answer 21

1. Wind turbines are usually put up in open places.
2. When the wind turns the blades, electricity is produced.
3. They produce no pollution once they are built.
4. And they do no permanent damage to the landscape (if removed goes back to normal).
5. However, they are not as reliable as others
6. They don’t produce electricity when wind stops
7. Turbines are also stopped if wind is too strong (to stop damage)
8. It also is impossible to increase supply when there’s demand for electricity.

Question 22

Describe solar cells effects on the environment and how they work.

Answer 22

1. Solar cells generate electricity directly from sunlight.
2. They create no pollution once they are built.
3. But quite a lot of energy is used to build them
4. Solar power only generates electricity during the day.
5. In sunny countries solar power is very reliable of energy.
6. It still fairly reliable in cloudy countries.
7. Like wind, you can’t increase the power output when there is extra demand.

Question 23

Describe the effects of geothermal power on the environment and how they work.

Answer 23

1. Geothermal power uses energy from the thermal energy store of hot rocks below the earth surface.
2. It can be used to generate electricity or to heat buildings.
3. Geothermal power is very reliable because the rocks are always hot.
4. Most geothermal power stations only have a small impact on the environment.

Question 24

Describe the effects of hydro-electric power on the environment and how they work.

Answer 24

1. Hydro-electric power usually involves building a big dam across a valley
2. The valley is usually flooded
3. Water is allowed to flow out through turbines, which generates electricity.
4. There is no pollution when it’s running
5. But there’s a big impact on the environment due to the flooding of the valley
6. Plants rot and release greenhouse gases which lead to global warming.
7. There’s no problem with reliability in countries that get rain regularly.
8. And it can respond straight away when there’s extra demand.

Question 25

Describe how wave power effects the environment and how it it works.

Answer 25

1. Turbines around the coast are turned by water waves and electricity is generated.
2. There is no pollution
3. But they disturb seabed and the habitats of animals
4. They are fairly unreliable , as waves tend to die down when wind drops

Question 26

Describe how tidal barrage effect the environment and how it works.

Answer 26

1. Tidal barrage are big dams (with turbines in them ) built across rivers.
2. Water passing through the turbines generates electricity.
3. The amount of energy generated changes the tides
4. But tidal barrages are very reliable, as we can predict the tires (we know what they are going to do)
5. There is no pollution.
6. But they do change the habitat of wildlife
7. And often fish are killed as they swim through turbines.

Question 27

What are bio fuels created from?

Answer 27

Plant products or animal dung.