Paper 2 Shtuff

Question 0

What is meant by the term resultant force? (1mark)

Answer 0

The overall force on an object

Question 1

Explain why a liquid cools down when it evaporates (5marks)

Answer 1

• There are attractive forces between molecules
• only the fastest molecules have enough energy to break away from other molecules
• these molecules escape from the surface of the liquid
• therefore the average speed/energy of the remaining molecules goes down
• the lower the average speed/energy of the molecules, the lower the temperature of the liquid

Question 2

Electric starter motors are always less than 100% efficient. Explain why. (3marks)

Answer 2

-not all the electrical energy is usefully transferred to -kinetic energy as -some is wasted as sound and thermal energy

Question 3

Suggest one way in which the teacher could obtain a more accurate value for the average background count rate (1mark)

Answer 3

-obtain count rate over a long period of time

Question 4

Describe the steps the student would take to obtain the data for the length of a pendulum (6marks)

Answer 4

• measure length of pendulum with ruler
• measure angle of bob and release
• time 10 swings
• change length and repeat
• divide each time/result by 10 to get one swing
• this is more accurate as it gives the answer to more d.p’s

Question 5

Suggest one reason why the anomalous result may have occurred (1mark)

Answer 5

• Thermometer misread

- Stopwatch misread

Question 6

What should the student have done when she realised that one if the results was anomalous? (2marks)

Answer 6

Done the result again 2 times to receive an average by taking a mean

Question 7

State and explain the effect of an increase in humidity on the cooling effect produced by the evaporation if sweat (2marks)

Answer 7

• reduces the cooling effect

- because the rate of evaporation of sweat/water decreases

Question 8

‘The specific latent gear of fusion of pure ice us 3.3 x 10(5) J/kg’
What does this statement mean?

Answer 8

It takes 3.3 x 10(5) J/kg to be able to change pure ice into water

Question 9

The fire in the stove uses wood as a fuel. The fire heats the Matt black case of the stove. How does the design of the stove help to improve the rate of energy transfer by infrared radiation? (2marks)

Answer 9

• Matt black is a good emitter of infrared radiation

- therefore absorbs the heat energy from the burning wood easily (more easily than shiny materials)

Question 10

Name one way in which energy is wasted by the stove. (1mark)

Answer 10

Light energy

Question 11

Two environmental advantages of using wood burning stoves instead of heaters that use electricity generated from fossil fuels (2marks)

Answer 11

• fossil fuels are non-renewable

- wood in carbon neutral and cheaper

Question 12

What happens to wasted energy from appliances? (1mark)

Answer 12

It is lost to the surroundings

Question 13

Give one environmental advantage to turning off electrical appliances when they are not being used. (1mark)

Answer 13

Less fossil fuels are burned

Question 14

What is geothermal energy? (1mark)

Answer 14

Energy from hot rocks in the earth

Question 15

Hydroelectric systems generate electricity using the energy of falling water. A pumped storage hydroelectric system can also be used as a way of storing energy for future use. Explain how. (2marks)

Answer 15

• water is pumped/moved

- up to a higher reservoir