Physics Past Paper Questions Flashcards
(20 cards)
Figure 1 shows a student walking on a carpet.
The student becomes negatively charged because of the friction between his socks
and the carpet.
Explain why the friction causes the student to become charged.
[2 marks]
transfer of electrons
from the carpet to the student
The negatively charged student touches a metal tap and receives an electric shock.
Explain why.
[3 marks]
there is a potential difference
between the student and the tap
which causes electrons /
charges to transfer from the
student
or
which causes electrons /
charges to transfer to the tap
which earths the charge
Some carpets have thin copper wires running through them. The student is less likely
to receive an electric shock after walking on this type of carpet.
Suggest why.
[2 marks]
carpet / copper has a low
resistance
lower / no build-up of charge (on
the student)
or
(so there is a) smaller / no
potential difference between
student and tap / earth
A student investigated how the resistance of a piece of nichrome wire varies with length.
Describe how the student would obtain the data needed for the investigation.
Your answer should include a risk assessment for one hazard in the investigation.
[6 marks]
- length measured
- length varied
- current measured
- potential difference measured
- repeat readings
- calculate resistance for each length
- resistance = potential difference
current - plot a graph of resistance against length
- hazard: high current
- may cause wire to melt / overheat
- may cause burns (to skin)
- use low currents
The maximum speed this cyclist can travel on a level road is 14 m/s.
How does cycling uphill affect the maximum speed of this cyclist?
Explain your answer.
[3 marks]
maximum speed is lower
because maximum power output
of cyclist is constant
(but) additional work is done
(against gravity)
or
gravitational potential energy (of
cyclist) is increased
Many householders are replacing their filament lamps with LED lamps which are more
energy efficient.
What does more energy efficient mean?
[1 mark]
a higher proportion / percentage
of the (total) power / energy
input is usefully transferred
or
higher (useful) power / energy
output for the same (total) power
/ energy input
The smoke alarm would not work with a radiation source that emits beta or
gamma radiation.
Explain why.
[2 marks]
beta and gamma radiation will
penetrate smoke
no change (in the count rate)
would be detected
Explain the ideal properties of a radioactive source for use in medical diagnosis.
[4 marks]
- short half-life or half-life of a few hours
- (short half-life means) less damage to cells / tissues / organs /
body - low ionising power
- (low ionising power means) less damage to cells / tissues /
organs / body - highly penetrating
- (highly penetrating means) it can be detected outside the body
- emits gamma radiation
A student investigated how the pressure exerted by a gas varied with the volume of the gas.
The student only recorded one set of results.
Give two reasons why taking repeat readings could provide more accurate data.
[2 marks]
any two from:
* calculate a mean
* reduces the effect of random
errors
* identify / remove anomalies
Figure 13 shows the position of the student’s eye when taking volume
measurements.
Explain what type of error would be caused if the student’s eye was not in line with
the level of the liquid in the tube. [2 marks]
random error
(because) eye position would
not be the same each time
(relative to the liquid)
If gas is compressed too quickly the temperature of the gas increases.
Explain how the temperature increase would affect the pressure exerted by the gas.
[2 marks]
(a temperature increase would)
increase the pressure in the
tube
(even if the volume was
constant)
(because a higher temperature
would mean) higher (average)
kinetic energy of molecules /
particles
Figure 14 shows a person using a bicycle pump to inflate a tyre.
The internal energy of the air increases as the tyre is inflated.
Explain why.
[2 marks]
work is done on the air (in the
tyre)
so the temperature (of the air)
increases
Nuclear power stations generate electricity through nuclear fission. Electricity can also
be generated by burning shale gas.
Shale gas is natural gas trapped in rocks. Shale gas can be extracted by a process
called fracking. There is some evidence that fracking causes minor earthquakes.
Burning shale gas adds carbon dioxide to the atmosphere.
Describe the advantages of nuclear power compared with the use of shale gas to
generate electricity.
[3 marks]
any three from:
* no carbon dioxide emitted (to
produce electricity)
* doesn’t cause global warming
* nuclear power doesn’t cause
earthquakes
* more energy released per kg
of fuel (compared to shale
gas)
What is the name of one fuel used in nuclear power stations?
[1 mark]
uranium
or
plutonium
Describe the process of nuclear fission.
[4 marks]
a neutron is absorbed by a
(large) nucleus
the nucleus splits into two
(smaller) nuclei
releasing energy (and gamma
rays)
and (two / three) neutrons
The power output of a coffee machine is 2.53 kW.
The mains potential difference is 230 V.
Calculate the current in the coffee machine.
[3 marks]
2530 = I × 230
l =2530/230
I = 11 (A)
The coffee machine heats water from 20 °C to 90 °C.
The power output of the coffee machine is 2.53 kW.
The specific heat capacity of water is 4200 J/kg °C.
Calculate the mass of water that the coffee machine can heat in 14 seconds.
[5 marks]
E = 2530 × 14
E = 35 420 (J)
35 420 = m × 4200 × 70
m =
35 420/4200 × 70
m = 0.12 (kg)
The power output of the turbine is directly proportional to the kinetic energy of the air
passing the blades each second.
Describe the effect on the power output when the wind speed is halved.
[3 marks]
mass of air passing the turbine
blades is halved which
decreases kinetic energy by a
factor of two
(wind speed is halved)
decreasing kinetic energy by a
factor of four
so kinetic energy decreases by
a factor of eight
At a different wind speed, the wind turbine has a power output of 388 kW.
The mass of air passing the wind turbine each second is 13 800 kg.
Calculate the speed of the air passing the blades each second.
Assume that the process is 100% efficient.
[3 marks]
388 000 = 0.5 × 13 800 × v2
v2=
(2 × 388 000)/13 800
v = 7.50 (m/s)
Bananas are a source of background radiation. Some people think that the unit of
radiation dose should be changed from sieverts to Banana Equivalent Dose.
Suggest one reason why the Banana Equivalent Dose may help the public be more
aware of radiation risks.
[1 mark]
people are able to compare a
radiation risk / dose / hazard to
the radiation dose from (eating)
bananas
