Physics End Of Year Exam

Question 1

The mean power output of the wind farm is 696 MW, which is enough power for 580 000 homes.
Calculate the mean power needed for 1 home.

Answer 1

1200 W

Question 2

On one day the demand for electricity in the UK was 34000 MW

Suggest two reasons why wind power was not able to meet this demand

Answer 2

Wind is unreliable

Wind turbines don’t turn when the wind is too strong/weak

Question 3

How oiling would affect the efficiency of the wind turbine

Answer 3

Efficiency would increase because amount of energy usually transferred would increase

Reduce friction

Question 4

Why people should be encouraged to use energy efficient electrical devices

Answer 4

More efficient devices waste less energy

More efficient devices need lower energy input

Question 5

Describe a method the student could use to determine the density of the rock

Answer 5

Fill a displacement can with water level with sprout

Place rock in water and collect displaced water

Measuring cylinder used to determine volume of displaced water

Volume or rock = volume of displaced water

Use of density = mass ➗ volume

Question 6

The student determined the density of the rock to be 2.55 +- 0.10 g/cm’.

Maximum and minimum density of the rock

Answer 6

Maximum = 2.65 (g/cm3)

Minimum = 2.45 (g/cm3)

Question 7

Which 2 types of rocks in Table 1 could be the type of rock the student had

Answer 7

Chalk or flint

Question 8

Why taking the measurements more than once may improve the accuracy of the density value

Answer 8

A mean can be calculated which reduces effect of random errors

Question 9

What equation links current, potential difference and power

Answer 9

Power = current x potential difference

P = V x I

Question 10

Why the zero error is not important

Answer 10

Only the change in reading/mass being observed

Question 11

What equation links efficiency, total power input and useful power output

Answer 11

Efficiency = useful power out ÷ total power

Question 12

A student rubbed a plastic rod with a cloth.
The rod became negatively charged and the cloth became positively charged

Explain why the cloth became positively charged

Answer 12

Friction causes electrons to move from the rod and on to the cloth

The charge on the rod is positive, as it has lost electrons

The charge on the cloth is negative, as it has gained electrons

Question 13

A negatively charged rod is held near an earthed conductor

Why does a spark jumps between the negatively charged rod and the earthed conductor

Answer 13

The large potential difference between the two objects causes negative electrons/charges to move through the air from the rod to the conductor

Question 14

What does an alpha particle consist of

Answer 14

Two protons and two neutrons tightly bound together

Question 15

Explain how the risk from internal contamination is different to the risk from external irradiation by a source of alpha radiation

Answer 15

Alpha radiation has a low penetrating power so external contamination will only act on an iradiated person’s skin

Question 16

What measuring instrument should be used to measure the volume of water

Answer 16

A graduated cylinder or a burette

Question 17

Some thermal energy was transferred to the surroundings while the water was being heated

Explain how this affected the student’s value for the specific latent heat of vaporisation of water

Answer 17

The transfer would result in a lower value

Some of the energy supplied to heat the water is lost to the environment

Question 18

Some of the water evaporated before its temperature reached 100 °C.

Explain how this affected the student’s value for the specific latent heat of vaporisation of water

Answer 18

Less energy required for remaining water for phase change from liquid to gas

Question 19

The braking distance of a car increases as the speed of the car increases

Give two other factors that increase the braking distance of a car

Answer 19

Wet/icy road conditions

Poor condition of brakes

Question 20

Why the driver’s reaction time affects the thinking distance of a car

Answer 20

Longer reation time = longer distance

Question 21

Which of the following conclusions can be made from figure F about reaction time of alcohol

Answer 21

Mean reaction time increases after drinking alcohol

Change in reaction time is not the same for all people after drinking alcohol

Question 22

Why does hailstone accelerate

Answer 22

There is a resultant force acting

Question 23

Why hailstone reaches terminal velocity

Answer 23

As velocity of hailstone increases air resistance increases

Until air resistance becomes equal to weight of the hailstone

Question 24

Why does terminal velocity increase with mass

Answer 24

As mass increase weight of hailstone increase

Question 25

Difference in maximum kinetic energy of a hailstone with a mass of 10g and hailstone mass 20g

Answer 25

Kinetic energy depends on mass and velocity

As mass increase so does terminal velocity

As mass doubles kinetic energy doubles

Question 26

What’s the same as 1 joule

Answer 26

1Nm

Question 27

Centre of mass

Answer 27

The point which weight may be considered to act

Question 28

1 property of a spring that makes it suitable

Answer 28

Deforms elastically so will return to its original shape