Energy

Question 1

Name the types of energy store:

Answer 1

Thermal
Kinetic
Gravitational potential 
Elastic potential 
Chemical 
Magnetic 
Electrostatic 
Nuclear

Question 2

Is energy a closed or open system?

Answer 2

Energy is transferred in a closed system so it can not enter or leave do the net change will always be zero and energy can never be destroyed

Question 3

Work done

Answer 3

Is another way of saying energy transferred and is done when a current flows or by a force of an object.
Work done : force x distance

Question 4

Do Falling objects transfers energy

Answer 4

Yes
Falling objects transfer energy
If a ball is dropped from a height it’s accelerated by gravity and does work. The energy from its gravitational potential energy is transferred to its kinetic energy store

Question 5

Kinetic energy is anything moving

What is the equation for kinetic energy?

Answer 5

E=1/2mv2

Kinetic energy = 1/2mass x speed2

Question 6

Lifting an object in a gravitational field requires work what is the equation to calculate gravitational potential energy

Answer 6

E=mgh

GPE=mass x gravitational field strength x height

Question 7

What is the gravitational field strength on earth?

Answer 7

9.8

Question 8

Stretching an object can transfer energy to elastic potential energy stores

Answer 8

To find the elastic potential in a stretched object you use

E=1/2ke2

Elastic potential energy=1/2spring content x extension2

Question 9

Different materials have different specific heat capacity’s what is a specific heat capacity?

Answer 9

The amount of energy needed to raise the temperature of a substance by 1degree

Question 10

What is the formula involving specific heat capacity?

Answer 10

Change in thermal energy = mass x specific heat capacity

Question 11

How to investigate specific heat capacity

Answer 11

1: Get a block of your material with two holes in it
2: Measure the mass of the block and wrap it in an insulating material
3: measure initial temperature then turn on power supply heating material and start timer
4: use the thermometer to measure rise every minute a
5: once you have enough recordings calculate the SHC

Question 12

Power is the rate of doing work and us measured in watts.

What is the equation for power?

Answer 12

P=E/T or P=W/T
Power = energy transferred / time
Power = work done / time

Question 13

What is conduction?

Answer 13

Conduction is the process where vibrating particles transfer energy to neighbouring particles

It mainly occurs in solids

Question 14

What is Convection?

Answer 14

Convection is where energetic particles move away from hotter to cooler regions

It only occurs in liquids and gases

Question 15

Why do solids not do convection?

Answer 15

Solids can’t do convection because unlike in gases and liquids the particles are not free to live and so the density doesn’t change

Question 16

How does lubrication reduce frictional forces?

Answer 16

Lubricants are used to make surfaces smoother and more easy to move. They reduce friction as they are liquids and easily slide between objects.

Question 17

What does insulation do?

Answer 17

Insulation reduces the rate of energy transfers by heating as it has low thermal conductivity so the rate of transfers is slower. This means a house for example would lose heat more slowly so it is insulated.

Question 18

How do cavity walls work?

Answer 18

Cavity walls are made of an inner and outer wall with an air gap in the middle. Because conduction can’t occur in the air it reduces the conduction. If there is then foam put in the wall convection Is also stopped to the wall is an insulator.

Question 19

How to investigate effectiveness of different insulators?

Answer 19

1: Boil a kettle and pour the water into a sealable container.
2: use a thermometer to measure the initial temp
3: seal container and leave for 5 mins and then record the temperature.
4. Repeat the experiment with your chosen insulators wrapped around the container.

Question 20

How do you calculate efficiency?

Answer 20

Efficiency = useful output energy transfers/total input energy transfer

Question 21

Most devices aren’t 100% energy efficient but some are name one:

Answer 21

Electric heaters as app the energy is electrostatic and transferred to thermal

Question 22

What is a non renewable energy resource and name some:

Answer 22

A fossil fuel or nuclear fuel that form underground and will run out as they can’t be reused

Eg
Coal
Oil
Gas

Question 23

What are renewable energy resources?

Answer 23

Resources that will never run out

Eg
Solar energy
Wind
Water wagers
Bio fuel 
Tides
Geothermal

Question 24

Non renewable resources are very damaging to the environment and cause a lot of green house gases when they are burned so what must we do

Answer 24

We must replace them with renewable energy sources that are less damaging and won’t run out