Oxford Revise AQA GCSE Physics | Chapter P19 answers

P19: Space

Answers

Extra information

Mark

AO / Specification reference

01.1

Sun

moons

moons/planets (in either order)/gravity

centripetal

1

1

3

1

AO1

4.8.1.1

4.8.1.3

01.2

correct similarity and difference e.g.,

both objects are in orbit

around different objects (planet around the Sun/Moon around a planet)

do not accept difference based on size

1

1

AO1

4.8.1.1

4.8.1.3

01.3

two correct similarities e.g.,

both objects are in orbit around a planet

due to the force of gravity

do not accept difference based on size

1

1

AO1

4.8.1.1

4.8.1.3

01.4

(the) Milky Way

1

AO1

4.8.1.1

02.1

the galaxy is moving away from Earth so the light from the galaxy is shifted to the red/B longer wavelength end of the spectrum.

1

1

AO1

4.8.2

02.2

the further the black lines are (red) shifted/ move towards the red end of the spectrum, the faster the galaxy is moving

1

AO2

4.8.2

02.3

the lines are shifted by a smaller amount

1

AO2

4.8.2

02.4

the line would be shifted towards A/to the left/to the blue end of the spectrum

1

AO3

4.8.2

03.1

a lower pitched sound has a longer wavelength

red-shifted light has a longer wavelength

1

1

AO2

4.8.2

03.2

the redshift is due to the Universe expanding (when observing galaxies) or stars moving away from us

the difference in the redshift is due to the speeds of the galaxies and stars as they move away from us

1

1

AO1

AO2

4.8.2

03.3

the force of gravity is pulling everything in the universe together

1

AO2

4.8.2

03.4

there is dark energy

they do not know what dark energy is or how it works

1

1

AO1

AO2

4.8.2

04.1

up and down

the direction of the oscillations of the wave is at right angles/perpendicular to the direction of motion of the wave

1

1

AO1

4.6.1.1

04.2

six waves

\(\frac{12}{6} = 2\ \rm{cm}/0.02\ \rm{m}\)

1

1

AO1

AO2

4.6.1.2

04.3

frequency (of the moving bar)

1

AO1

4.6.1.2

04.4

count the number of times the bar moves up and down per second

measure the time for a (large) number of movements up and down

(divide the number of movements by the time)

one mark for indication of frequency

one mark for indication of measuring a number of oscillations of the bar

1

1

AO2

4.6.1.2

05.1

bigger than

nebula

supernova

1

1

1

AO1

4.8.1.2

05.2

(nuclear) fusion

1

AO1

4.8.1.1

05.3

supernovae explode scattering elements throughout the universe

gravity pulls them together to make stars and planets

1

1

AO2

4.8.1.1

4.8.1.2

4.8.1.3

06.1

the force is at right angles/perpendicular to the direction of motion at all times/ centripetal/towards the centre of the circle

1

AO1

4.8.1.3

06.2

one point for correctly plotting points

one point for line of best fit

2

AO2

AO3

4.8.1.3

06.3

500

days

allow 450 – 550

1

1

AO2

AO1

4.8.1.3

06.3

the distance travelled by Planet e is approximately double that of Marjiriti

the time taken for the orbit of Planet e is about 3 times that of Marjiriti

\(\rm{speed}\ =\ \frac{\rm{ditance}}{\rm{time}}, \rm{so\ speed\ of\ planet\ e\ is\ about}\ \frac{2}{3}\ \rm{that\ of\ Marjiti}\)

1

1

1

AO3

4.8.1.3

07.1

the universe began as a massive explosion from

a very small, hot, dense region of space

one mark for ‘explosion’

one mark for mentioning one or two of ‘small’, ‘hot’ and ‘dense’

two marks for all three of ‘small’, ‘hot’ and ‘dense’

3

AO1

4.8.2

07.2

an object moving away twice as fast as another object will double the distance between them in a given time interval

showing that the universe is expanding

1

AO2

4.8.2

07.3

one mark for straight line graph labelled P

one mark for curved line graph labelled I

one mark for line labelled I above line labelled P

\(
\begin{array}{lr}
\rm{the\ gradient} = \frac{\rm{speed}}{\rm{distance}}\\
\rm{speed} = \frac{\rm{distance}}{\rm{time}}\\
\rm{so\ units\ of\ gradient} = \frac{1}{\rm{time}}
\end{array}
\)

3

1

1

1

AO1

AO2

4.8.1.1

4.8.1.2

4.8.1.3

4.8.2

10

Level 3: Correctly describes the formation of a protostar, conditions for fusion and reasons for equilibrium. Well organised answer.

5-6

AO1

AO2

4.8.2

Level 2: Describes the formation of a protostar, lacks some details about conditions for fusion or reasons for equilibrium. Some organisation of answer.

3-4

Level 1: Some description of formation but lacking details about fusion or equilibrium. Answer shows poor organisation.

1-2

No relevant content.

0

Indicative content:

  • the Sun was formed from a cloud of dust and gas/nebula
  • that came together due to the force of gravity
  • to form a protostar
  • the gas/hydrogen eventually moves fast enough to start fusion reactions
  • producing energy/radiation that expands the gas that makes up the star

08.2

a small mass star (the same mass as the Sun) will become a red giant, white dwarf, and black dwarf

a larger mass star than the Sun will become a red supergiant, supernova, and neutron star or black hole.

3

3

AO1

4.8.2

09.1

there was not enough evidence to support her conclusion/the conclusion opposed what was thought at the time/people did not want to change what they thought

1

AO3

4.8.1.2

09.2

more people had studied the evidence/more research had been done by other scientists/ published in journals/had time to get used to the idea changing

1

AO3

4.8.1.2

09.3

four

2

1

1

AO2

4.8.1.2

09.4

two helium nuclei fuse to produce Be/beryllium

three helium nuclei fuse to produce C/carbon

1

1

AO2

4.8.1.2

09.5

fusion involves the joining of nuclei

which are positively charged so repel

larger nuclei mean more charge, and a bigger repulsive force

1

1

1

AO2

4.8.1.2

09.6

iron

1

AO2

4.8.1.2

10.1

the bung

1

AO2

4.8.1.3

10.2

the tension in the string

allow the weight of the masses

do not allow ‘masses’

1

AO2

4.8.1.3

10.3

any two correct sources e.g.,

  • reaction time when using a stopwatch
  • parallax/not reading straight when using a ruler
  • not keeping the speed constant/circle horizontal

one mark for each correct answer up to a maximum of two marks

2

AO3

4.8.1.2

10.4

if the radius is smaller, the speed is larger

1

AO2

4.8.1.3

10.5

friction/air resistance

1

AO2

4.8.1.3

11.1

W, X, Z

one mark for one or two correct

two marks for all correct

2

AO1

AO2

4.8.2

11.2

pull the elastic to make it longer

it shows that as space expands, the wavelength of the radiation increases

1

1

AO3

4.8.2

11.3

to demonstrate phenomena that are difficult/too big/too small to see

to make predictions/explanations of observations

1

1

AO2

12.1

accelerating

then moving with a steady speed/velocity

downwards

1

1

1

AO2

4.5.6.1.4

12.2

stationary

1

AO2

4.5.6.1.4

12.3

draw a tangent to the curve at five seconds

calculate the slope of the tangent.

\(
\begin{array}{lr}
\textrm{velocity} = \frac{-4.0\ -\ (-1.8)}{7.6-0}\\
= -0.29\ \rm{m/s}
\end{array}
\)

either negative sign or explicit statement that the velocity is downwards

1

1

1

AO2

4.5.6.1.4

4.5.6.1.5

12.4

one mark for graph showing initial negative velocity, then horizontal line showing constant negative velocity

one mark for section at zero velocity in the middle

one mark for positive velocity, then horizontal line showing constant positive velocity

one mark for curved line joining sections

4

AO3

4.5.6.1.4

4.5.6.1.5

13.1

the forces on it are unbalanced/there is a resultant force on it

the upthrust/force of the water on the balloon is greater

than the weight/force of gravity on the balloon

1

1

AO2

4.5.5.1.1

4.5.4.1.2

13.2

pressure = height of column × density of water × gravitational field strength

= 3 × 1000 × 9.8

= 29 400

Pa

1

1

1

AO2

AO1

4.5.4.1.2

13.3

reading will be higher

because the correct reading is atmospheric pressure (about 101 kPa) plus pressure due to the water column

1

1

AO2

4.5.4.1.2

4.5.5.2

14.1

independent – mass of moving trolley

dependent – velocity of combined trolleys

1

1

AO2

4.5.6.1.3

14.2

control variables – mass of stationary trolley/speed of moving trolley

2

AO3

4.5.6.1.3

14.3

the uncertainty is the range of repeat measurements divided by two

\(\rm{range\ is\ between\ 0.3\ and\ 0.01\ so\ the\ largest\ uncertainty} = \frac{0.3}{2} = 0.15\)

1

1

AO1

AO2

4.5.6.1.3

14.4

yes, it should go through (0,0)

if the mass of the trolley is zero, it will have no momentum, so the momentum/velocity after the collision will be zero

one mark for correctly plotting points

one mark for line of best fit

2

1

1

AO2

AO3

4.5.6.1.3

14.5

initial momentum = final momentum

initial momentum = 0.1 × 2.0 = 0.2 kg m/s

final momentum = (0.1 + 0.2) × final combined velocity

0.2 = 0.3 × final combined velocity

\(
\begin{array}{lr}
\rm{final\ combined\ velocity} = \frac{0.2}{0.3} = 0.67\ \rm{m/s}\\
\rm{percentage\ difference} = \frac{0.67\ -\ 0.63}{0.67} \times 100\\
= 6.0\%
\end{array}
\)

one mark for giving answer to two significant figures

1

1

1

1

1

1

AO1

AO2

4.5.7.2

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