AstrophysicsEdexcel IGCSE Physics: Topic test

20 questions, 54 marks

Edexcel IGCSE Physics

Astrophysics topic test

Total 54 marks

Name

Class

Date

1
An astronomy student is studying Europa, one of Jupiter's moons, which orbits Jupiter in a circular path of radius 6.7 x 10^8 m, completing one full orbit every 3.06 x 10^5 s (about 3.55 days).
(a)
Which equation is used to calculate the orbital speed of a moon from its orbital radius and time period?
[1 mark]
Av = 2 x pi x r / T
Bv = pi x r / T
Cv = 2 x pi x r x T
Dv = r / (2 x pi x T)
(b)
A comet has a highly elliptical orbit around the Sun, unlike Europa's circular orbit around Jupiter. Which statement correctly compares the comet's speed at different points of its orbit?
[1 mark]
AThe comet moves at a constant speed throughout its orbit, like a planet in a circular orbit
BThe comet moves fastest when closest to the Sun and slowest when furthest away
CThe comet moves slowest when closest to the Sun
DThe comet's speed does not depend on its distance from the Sun
(c)
Calculate the orbital speed of Europa.
[2 marks]
Total for question 1: 4 marks
2
A school astronomy project uses colour data captured by a robotic telescope to sort a sample of stars into groups. Two of the stars in the sample, Star P and Star Q, are found to have very different colours: Star P appears distinctly blue-white, while Star Q appears distinctly red.
(a)
What does the difference in colour between Star P and Star Q mainly tell astronomers about the two stars?
[1 mark]
AStar P is much older than Star Q
BStar P is much smaller than Star Q
CStar P has a much higher surface temperature than Star Q
DStar P is much closer to Earth than Star Q
(b)
Star Q is later identified as being in the red giant stage of its life. Which stage of stellar evolution, for a star of similar mass to the Sun, comes immediately after the red giant stage?
[1 mark]
AMain sequence star
BNebula
CBlack hole
DWhite dwarf
(c)
State the stage that comes before the main sequence stage, and the stage that comes after the red giant stage, in the evolutionary sequence of a star of similar mass to the Sun.
[2 marks]
Total for question 2: 4 marks
3
For a physics coursework project, a student uses archived spectral data to study light from a distant galaxy. A hydrogen absorption line that has a reference (laboratory) wavelength of 486 nm is measured in the galaxy's spectrum at a wavelength of 495 nm.
(a)
Explain what the increase in wavelength of the hydrogen line, compared with its reference wavelength, tells the student about the motion of the galaxy relative to Earth.
[3 marks]
(b)
Calculate the velocity at which the galaxy is moving away from Earth. (speed of light c = 3.0 x 10^8 m/s)
[4 marks]
Total for question 3: 7 marks
4
A radio astronomy group builds a small satellite instrument to measure faint microwave radiation arriving uniformly from every direction in the sky. This radiation, known as the cosmic microwave background (CMB), is found to have almost exactly the same intensity and wavelength no matter which direction the instrument is pointed, once the effects of our own galaxy have been removed from the data.
(a)
Explain how the existence of the cosmic microwave background (CMB), together with the observed red-shift of distant galaxies, supports the Big Bang theory of the origin of the universe.
[6 marks]
(b)
Explain how our own galaxy fits into the overall structure of the universe, and explain why the microwave radiation from our own galaxy had to be removed from the satellite's data before the more distant CMB signal could be studied.
[6 marks]
Total for question 4: 12 marks
5
A robotics engineer is designing an uncrewed lander to place a 40 kg scientific instrument package on the surface of the Moon, where the gravitational field strength is 1.6 N/kg, compared with a gravitational field strength of 10 N/kg on the surface of the Earth.
(a)
Which equation is used to calculate the weight of the instrument package from its mass and the gravitational field strength at a location?
[1 mark]
Ag = W x m
BW = m x g
CW = m / g
DW = m + g
(b)
Why is the gravitational field strength at the surface of the Moon so much smaller than at the surface of the Earth?
[1 mark]
AThe Moon has a much smaller mass than the Earth
BThe Moon is much further from the Sun than the Earth
CThe Moon has no atmosphere
DThe Moon does not rotate on its axis
(c)
Calculate the weight of the 40 kg instrument package on the surface of the Moon.
[2 marks]
Total for question 5: 4 marks
6
An online star catalogue lists a star, currently in its main sequence stage, with a mass around 15 times that of the Sun, much greater than the Sun's mass.
(a)
Because this star's mass is much greater than the Sun's, which stage will it evolve through after leaving the main sequence, that a Sun-like star does not go through?
[1 mark]
AA red giant
BA nebula
CA white dwarf
DA supernova explosion
(b)
What can be left behind after a very massive star explodes as a supernova?
[1 mark]
AA new main sequence star
BA nebula that immediately reforms into the same star
CA neutron star or a black hole
DNothing at all remains
(c)
State two ways in which the evolutionary path of this massive star, after it leaves the main sequence, differs from the evolutionary path of a star with a mass similar to the Sun.
[2 marks]
Total for question 6: 4 marks
7
Observations show that almost all distant galaxies show red-shifted light, and that more distant galaxies generally show a greater degree of red-shift than closer ones.
(a)
Explain what is meant by the red-shift of light from a galaxy, and state what causes it.
[3 marks]
(b)
Explain why the observation that more distant galaxies generally show a greater red-shift than closer ones provides evidence that the universe is expanding.
[4 marks]
Total for question 7: 7 marks
8
An astronomy class studies a nearby young star cluster that formed recently from the same nebula. Several of the young stars in the cluster are found to be orbiting each other in binary pairs, held together by the gravitational force between them, while the whole cluster of stars is itself held together by the combined gravitational pull of all its stars.
(a)
Explain how the stars in this young cluster are thought to have formed from the original nebula, and describe what determines whether an individual star in the cluster will eventually evolve like the Sun or evolve like a much more massive star.
[6 marks]
(b)
Explain, in terms of gravitational force, why pairs of stars in the cluster orbit each other, and why the whole cluster of stars stays held together rather than drifting apart.
[6 marks]
Total for question 8: 12 marks

End of questions