physics

Question 1

A spring is elastically deformed.

What is meant by ‘elastically deformed’? (2)

Answer 1

(the spring) will return to its original shape/length
when the force is removed

Question 2

Explain why a star (the same mass as the Sun) remains stable while it is in the main sequence stage of its life cycle? (2)

Answer 2

the inwards gravitational force and the outwards force as a result of fusion
are balanced / in equilibrium

Question 3

Describe what will happen to a star (the same mass of the Sun) between the main sequence stage and the end of the star’s life cycle.

Include the names of the stages in the life cycle of the star. (3)

Answer 3

(the star) will expand to become a red giant
(then it will) collapse to become a white dwarf
(then it will) cool to become a black dwarf

Question 4

Give three uses of ultraviolet light.

Answer 4

energy efficient lamps
tan
sterilise surgical equipment
kill microbes
attract insects
detecting forged banknotes
water purification

Question 5

How could you determine the speed of water waves in a ripple tank without measuring the wavelength of the wave? (3)

Answer 5

use a metre ruler to measure the distance travelled by the wave
use a stopwatch to measure the time taken for the wave to travel that distance
find speed by dividing the distance travelled by the time taken

Question 6

Explain how a moving-coil loudspeaker produces a sound wave. (4)

Answer 6

• the current creates a magnetic field
• which interacts with the permanent magnetic field
• this causes a resultant force causing the cone to move
• when the direction of the current reverses the force on the cone reverses (causing sound waves)

Question 7

State two factors that would affect the size of the centripetal force of a satellite. (2)

Answer 7

radius of the orbit / height above the Earth
speed of the satellite
mass of the satellite

Question 8

In 2012 a skydiver jumped from a helium balloon 39 000 metres above the Earth’s surface.
The skydiver reached a maximum speed of 377m/s.

Jumping 39 000 metres allowed the skydiver to reach a much higher speed than a skydiver jumping from 4000 metres.

Explain why. (3)

Answer 8

at higher altitudes, the air is less dense
so air resistance is lower
(so) it the skydiver can fall longer before reaching terminal velocity

Question 9

A skydiver jumps out of a plane at 4000m.
Explain the changing motion of the skydiver in terms of forces acting on the skydiver. (4)

Answer 9

• when he jumps his weight downwards is greater than air resistance / resultant force downwards
• (resultant force causes) acceleration
• (which) causes air resistance to increase
  resultant force decreases to 0
• (and) the skydiver falls at terminal velocity

Question 10

It is illegal for train drivers to drink alcohol before driving a train.

Explain how drinking alcohol would affect the stopping distance of a train. (3)

Answer 10

• alcohol increases reaction times
• which will increase thinking distance so stopping distance will increase
• because stopping distance includes both braking distance and thinking distance

Question 11

Which subatomic particle was discovered first?

Answer 11

electron

Question 12

Which model was developed last?

1. Bohr
2. Nuclear
3. Plum pudding
4. Tiny sphere that cannot be divided

Answer 12

Bohr

Question 13

The idea of obtaining power from nuclear fusion was investigated using models.

The models were tested before starting to build the first commercial nuclear fusion power station.

Suggest three reasons why models were tested.

Answer 13

to make sure the fusion process is possible
to develop an understanding of the process
to make adaptations to the process
to assess the efficiency of the process
to make predictions
assess safety risks
to assess environmental impact
set-up cost is lower (for small scale experiments)

Question 14

A red filter is placed in front of a spotlight.

The spotlight is directed at a blue object.

Explain why the object appears black. (3)

Answer 14

only red is transmitted by the filter
blue object absorbs red light
no light is reflected by the (blue) object

Question 15

What is meant by a zero error?

Answer 15

when (measuring device) displays a reading when not connected / should be zero

Question 16

A torch uses an LED.

The cells that were put into the torch were the wrong way round.

Explain why the torch will not work. (2)

Answer 16

charge will not flow through a diode in the reverse direction
because it / the diode has a very high resistance (in the reverse direction)

Question 17

Give three environmental advantages of using a gas-fired power station to generate electricity compared with using a coal-fired power station.

Answer 17

no sulfur dioxide released
doesn’t cause acid rain
no particulates released
doesn’t cause global dimming
less carbon dioxide released (per kg of fuel)
less global warming
allow climate change / greenhouse gases
no solid waste
gas mining is less destructive than coal mining

Question 18

Nuclear fission releases energy.

Describe the process of nuclear fission inside a nuclear reactor. (4)

Answer 18

neutron absorbed by uranium nuclei
nucleus splits into two parts / two lighter daughter nuclei are formed
2 or 3 neutrons are released
and gamma rays are emitted

Question 19

Explain the advantage of radioactive waste having a shorter half-life. (2)

Answer 19

activity decreases quickly / faster
risk of harm decreases quickly / faster

Question 20

Explain why adding resistors in parallel decreases the total resistance. (2)

Answer 20

there are more pathways for charge to flow
so the total current increases (when potential difference stays the same)

Question 21

There is a switch in a mains electricity lighting circuit in a house.

The electrician replaced the switch.

The electrician would have recieved an electric shock unless the circuit was disconnected from the mains supply.

Explain why. (3)

Answer 21

• wire in the switch is live
• electrician is earthed
• so there would’ve been a large potential difference between the electrician / earth and the (live) wire (if the electrician touched it / the live wire)

Question 22

The temperature of the helium in a balloon was increased.

The mass and volume of helium in the balloon remained constant.

Explain why the pressure exerted by the helium inside the balloon would increase. (4)

Answer 22

• particles have more kinetic energy
• so there will be an increased frequency of collisions with the walls of the balloon per unit time
• (also) greater forces will be exerted in collisions
  greater force exerted on the same area (increasing the pressure)

Question 23

Describe how an investigation could be improved to reduce the effect of random error. (2)

Answer 23

repeat (the investigation)
ignore anomalies and calculate a mean

Question 24

Some stars are much more massive than the Sun.

Describe the life cycle of stars much more massive than the Sun, including the formation of new elements. (6)

Answer 24

Level 3: Scientifically relevant facts, events or processes are identified and given in detail to form an accurate account.

Level 2: Scientifically relevant facts, events or processes are identified and their relevance is clear. The account is not fully accurate.

Level 1: Facts, events or processes are identified and simply stated but their relevance is not clear.

Indicative content:

• fusion produces new elements
• cloud of gas / hydrogen and dust or nebula
• pulled together by gravity
• causing increasing temperature (to start the fusion process)
• (to become a) protostar
• hydrogen nuclei fuse to form helium nuclei
• and the star becomes main sequence
• hydrogen begins to run out
• helium nuclei fuse to make heavier elements
• up to iron
• the star expands (to become a)
• red supergiant
• (the star collapses rapidly) and explodes
• in a supernova
• creating elements heavier than iron
• and distributing them throughout the universe
• leaving behind a neutron star
• or a black hole

Question 25

A ray of light from a ray box should be as narrow as possible. Explain why using a wider ray would give less accurate results than using a narrower ray. (2)

Answer 25

it is harder to judge where the centre of a wider ray is causing a larger uncertainty / increasing random errors

Question 26

The ice hockey players wear protective pads filled with foam. Explain how the protective pads help to reduce injury when the players collide. (3)

Answer 26

the foam increases the contact time taken during a collision which decreases the rate of change of momentum which decreases the force

Question 27

A portable power supply has an alternator connected to a transformer. The transformer can be adjusted to have different numbers of turns on the secondary coil. Suggest why. (2)

Answer 27

to vary the (output) potential difference so that you don’t need a different alternator / generator for each / every (type of) device

Question 28

Suggest the purpose of slip rings in an alternator.

Answer 28

to provide continuous contact (between the coil and brushes)

Question 29

A remote control transmits radio waves to a car’s aerial. The car aerial is connected to an electrical circuit. Describe what happens in the electrical circuit when the car aerial absorbs the radio waves. (2)

Answer 29

(alternating) current is induced (in the circuit) with the same frequency as the radio waves

Question 30

Explain why the car has a maximum speed. (4)

Answer 30

- there is a maximum forward / driving force (provided by the motor) - as the speed of the car increases air resistance increases - until the resultant force is zero / until the forces are balanced / in equilibrium / until the size of the air resistance force is equal to the size of the forward force - so the car can no longer accelerate / has reached terminal velocity

Question 31

The National Grid ensures that fossil fuel power stations in the UK only produce about 33% of the total electricity they could produce when operating at a maximum output. Suggest two reasons why.

Answer 31

so as to not make unnecessary environmental impact conserves fuel reserves spare capacity to compensate for unreliable renewable resources provides spare capacity in case of power station emergency shut-down

Question 32

A student models the random nature of radioactive decay using 100 dice. He rolls the dice and removes any that land with the number 6 facing upwards. He rolls the remaining dice again. The student repeats this process a number of times. Give two reasons why this is a good model for the random nature of radioactive decay. (2)

Answer 32

you can not predict **which** dice / atom will ‘decay’ you can not predict **when** a dice / atom will ‘decay’

Question 33

A teacher wears polythene gloves as a safety precaution when handling radioactive materials. The polythene gloves do not stop the teacher’s hands from being irradiated. Explain why the teacher wears polythene gloves. (2)

Answer 33

to prevent contamination which would cause damage / irradiation over a longer period of time

Question 34

In what order was the elctron, neutron, nucleus and proton discovered?

Answer 34

electron, nucleus, proton, neutron

Question 35

Explain why alpha particles are deflected when they are directed at a gold nucleus. (2)

Answer 35

- alpha particles and (gold) nucleus are both positively charged - (and) like charges repel

Question 36

A student left a thermometer in an iron block for a few minutes before recording the initial temperature. Suggest why.

Answer 36

so the thermometer temperature was the same as the iron block

Question 37

Why do did some alpha particles get deflected at a greater angle than others? (2)

Answer 37

- they passed closer to the nucleus - so they experienced a greater force

Question 38

Ice changed from solid to a liquid and increasaed in temperature to 5 degrees celsius. Explain the changes in the arrangement **and** movement of the particles as the ice melted and the temperature increased to 5 degrees celsius. (6)

Answer 38

Level 3: Relevant points (reasons / causes) are identified, given in detail and logically linked to form a clear account. Level 2: Relevant points (reasons / causes) are identified, and there are attempts at logical linking. The resulting account is not fully clear. Level 1: Points are identified and stated simply, but their relevance is not clear and there is no attempt at logical linking. Indicative content * particles in a solid are in a regular pattern * particles in a liquid are in a random arrangement * particles in a solid are vibrating about fixed positions * particles in a liquid are moving freely * as the ice changes to water the temperature remains constant * because as the ice changes to water the potential energy of the particles increases * as the water warms the particles move faster * so the kinetic energy of the particles increases * internal energy is the total kinetic and potential energy of all the particles *ignore any references to density of ice vs liquid water ignore any references to spacing of particles*

Question 39

A solar power system is installed in the remote village in addition to the hydroelectric generator. Explain why this improves the reliability of th electricity supply to the village. (2)

Answer 39

- druing the summer power output from the solar panels would be higher - so there would be **less variation** in total power output

Question 40

The half-lives of some radioactive isotopes are given below. Nitrogen-18: 0.62s Nitrogen-17: 4.17s Fluorine-17: 64.37s Fluorine-18: 6584.34s All of the isotopes above emit beta radiation. Explain which isotope would cause the biggest risk to a person's heallth based only on the half-life of each isotope. (3)

Answer 40

- Nitrogen-18 - greatest activity - greatest dose of radiation absorbed (per second)

Question 41

Flurorine-18 has a half life of 6584.34s. A sample of fluorine-18 has an activity that is one quarter o its original activity. Calculatae the age of the sample of fluorine-18. (2)

Answer 41

- two half-lives - 13168.68s

Question 42

Explain how an electron can move up and down between energy levels in an atom. (2)

Answer 42

- to move to a higher energy level the electron absorbs energy from electromagnetic radiation - to move to a lower energy level the electron emits energy in the form of electromagnetic radiation

Question 42

Describe the difference between irradiation and contamination. (2)

Answer 42

- irradiation is the **exposure** of an object/person to radiation - contamination is the presence of radioactive material / atoms on an object / person

Question 43

Workers in nuclear power stations are monitored to check the radiation they emit. A worker stands 1 cm away from a radiation detector. The amount of radiation the worker emits is recorded. Explain why the worker needs to stand close to the radiation detector. (2)

Answer 43

- some radioactive materials emit alpha radiation - (which) has a very short range in air

Question 44

How would you find negative values of current and potential difference in an investigation?

Answer 44

reverse the connection to the power supply

Question 45

A student conducts an experiment investigating the IV characteristics of a filament lamp. The power output of the lamp is 1.0W when the potential difference across the lamp is 5.0V. The student predicts that the pwer output would be 4.0W if the potential difference was doubled. Explain why the student is **not** correct. (2)

Answer 45

- (for power output to quadruple) potential difference and current would both have to double - (however) current doesn't double because resistance increases

Question 46

The baby bouncer should not be used with babies that have a mass greater than 12kg. Suggest **one** reason why.

Answer 46

- spring may become permanently extended - extension of the spring may be too great *ignore reference to limit of proportionality*

Question 47

Explain why pressure increases as more air is pumped into a tire. (2) Volume and temperature of the air inside the tire do **not** change.

Answer 47

- more particles - greater number of collisions between tyre (walls) per second / unit (of) time

Question 48

Explain why the air pressure in a car tyre changes if the temperature of the air in the tyre increases. (4)

Answer 48

- (as temperature increases the) air particles have greater (mean) **kinetic energy** - (so) more / increased frequenct of collisions with tyre (walls) per second - (and) greater force in each collision - greater (mean) force **per square metre** causes greater pressure (on wall of tyre)

Question 49

The specific heat capactiy of ice is less than the specific heat capacity of water. Explain how a figure with temperature on the y-axis and time on the x-axis would show this. (2)

Answer 49

- there would be a **steeper gradient** for ice than water - which means less energy is needed to increase the temperature by a fixed amount

Question 50

The specific latent heat of fusion of ice is less than the specific latent heat of vaporisation of water. Explain how a figure with temperature on the y-axis and time on the x-axis would show this. (2)

Answer 50

- it would take more time for water to vaporise than ice to melt - so less energy is needed to change state from solid to liquid (than liquid to solid)

Question 51

A student measured the volume of a apple once. The volume measurement **cannot** be used to show that an experiment involving the apple gave precise readings. Give the reason why. (1)

Answer 51

repeat readings (of volume) need taking to show that the readings are close together

Question 52

When the volume of gas inside a syringe increased, the pressure on the inside walls of the syringe decreased. Explain why. (3)

Answer 52

- there is more time between collisions of particles and the walls of the syringe **or** there are less frequent collisions between the particles and the walls of the syringe - (causing) a lower (average) force on the walls of the syringe - (and) pressure is the total force per unit area

Question 53

Explain what type of error would be caused if a student's eye was **not** in line with the level of a liquid in a measuring cylinder. (2)

Answer 53

- random error - because the eye level would not be the same each time

Question 54

The power output of a 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)

Answer 54

- mass of air passing the turbine blades is halved which decreases kinetic energy by a factor of 2 - (wind speed is halved) decreasing kinetic energy by a factor of 4 - so kinetic energy decreases by a factor of 8

Question 55

A polonium (Po) nucleus decays by emitting an alpha particle and forming a lead (Pb) nucleus. Po → Pb + α The lead (Pb) nucleus then decays by emitting a beta particle and forms a bismuth (Bi) nucleus. Pb → Bi + β The bismuth (Bi) nucleus then decays by emitting a beta particle and forms a polonium (Po) nucleus. Bi → Po + β Explain how these three decays result in a nucleus of the original element, polonium. (3)

Answer 55

- one alpha decay would decrease proton number by 2 - two beta decays would increase proton number by 2 - so the proton / atomic number of the final nucleus is the same as the proton / atomic number of the original nucleus

Question 56

Give 3 man-made sources of backround radiation.

Answer 56

- radioactive waste from nuclear power stations - nuclear weapons (testing) - x-rays - radiotherapy - named nuclear disaster e.g. Chernobyl / Fukushima / Three Mile Island.

Question 57

Explain how the process of nuclear fuson leads to the release of energy. (2)

Answer 57

- lighter nuclei join to form heavier nuclei - some of the mass is converted to energy

Question 58

Explain why contamination of the inside of the human body by a radioactive material that emits alpha radiation is highly dangerous. (3)

Answer 58

- alpha radiation is highly ionising - causing an increased risk of cancer **or** organ failure **or** radiation sickness / poisoning **or** mutation of genes / DNA **or** damage to cells / tissues / organs - until the radioactive material is removed / excreted **or** activity of radioactive material reaches / approaches background radiation levels

Question 59

A smoke alarm that detects smoke using alpha radiation would not work with a radiation source that emits beta or gamma radiation. Explain why. (2)

Answer 59

- beta and gamma will penetrate smoke - so no change (in count rate) will be detected

Question 60

Explain how the paths of the alpha particles in the alpha particle scattering experiment were used to develop the nuclear model of the atom. (4)

Answer 60

- most alpha particles pass straight through the atom - which shows that the atom is mostly empty space - very few alpha particles are deflected through a large angle - which shows the atom contains a nucleus where the mass / charge of the atom is concentrated

Question 61

Explain why a spark jumps between a negatively charged rod and an earthed conductor. (3)

Answer 61

- (there is a large) potentital difference between the two objects - (causing negative) electrons to move (through the air) - (from the rod) to the conductor

Question 62

Person A took a longer time to run up a set of stairs than Person B, but they had the same power output. What conclusion can be made about the person A's mass?

Answer 62

A's mass was greater than B's

Question 63

In addition to power input, light bulbs should also be labelled with the rate at which they emit visible light. Suggest why.

Answer 63

- bulbs also transfer thermal energy - the efficiency of the light bulb also needs to be considered

Question 64

Engineers have developed a way of charging electric cars while they are driving along the road. Coils of wire buring under the road transfer energy ot the car's battery as the car is passing over the coils. Suggest two advantages of using this method to charge electric cars compared with plugging them into the mains electricity supply. (2)

Answer 64

- recharging is a continuous process - more cars can be charged at the same time - fewer cells needed in the car

Question 65

When electric cars are not being driven, energy stored in their batteries could be used to meet sudden peaks in electricity demand. Suggest how.

Answer 65

- when cars are plugged in - the energy from car batteries could be transferred back to the National Grid

Question 66

As a person moves down a zip wire, their increase in kinetic energy is less than their decrease in gravitational energy. Explain why. (2)

Answer 66

- friction **or** air resistance - causes thermal energy to be transferred to the surroundings

Question 67

Explain why different people have different speeds at the end of a zip wire. (2) | Give two different reasons and explain.

Answer 67

- different people have different surface areas - so will be affected by air resistance differently **or** - people may have different masses - so their terminal velocity will be different **or** - initial speed may not be zero - which would add to the total energy of the system