AstrophysicsIB MYP Physics: Topic test

20 questions, 54 marks

IB MYP Physics

Astrophysics topic test

Total 54 marks

Name

Class

Date

1
A family from Oslo, Norway, spends December in Sydney, Australia, where it is hot summer weather and people are swimming at the beach. Back home in Oslo it is cold, with only a few hours of daylight each day.
(a)
What is the main cause of the seasons on Earth?
[1 mark]
AEarth moves much closer to the Sun in summer and much further away in winter
BEarth's axis is tilted as it orbits the Sun
CEarth rotates once every 24 hours
DThe Moon's gravity pulls on Earth's atmosphere
(b)
Which statement about Earth in December is correct?
[1 mark]
AThe Northern Hemisphere is tilted towards the Sun
BBoth hemispheres are tilted equally towards the Sun
CThe Southern Hemisphere is tilted towards the Sun
DEarth is at its closest to the Moon
(c)
Explain why Sydney has longer days and a higher Sun in the sky in December than in June.
[2 marks]
Total for question 1: 4 marks
2
The weather agency of the Philippines tracks typhoons using two satellites. One is in a low polar orbit about 800 km above Earth and passes over the poles roughly 14 times a day. The other is in a geostationary orbit about 36 000 km above the equator and always stays above the same place on Earth.
(a)
What is the orbital period of the geostationary satellite?
[1 mark]
AAbout 90 minutes
B12 hours
C365 days
D24 hours
(b)
Which statement explains why the geostationary satellite stays above the same place on Earth?
[1 mark]
AIt orbits above the equator in the same direction as Earth spins, taking one day
BIt does not move, because there is no gravity so far from Earth
CIt orbits over the poles while Earth turns beneath it
DIt is held in place by the Moon's gravity
(c)
State one advantage of each type of orbit for monitoring a typhoon.
[2 marks]
Total for question 2: 4 marks
3
Astronomers in South Korea track a comet whose orbit takes it from 0.6 AU from the Sun at its closest to 35 AU at its farthest. One astronomical unit (AU) is the average distance from Earth to the Sun. Neptune is 30 AU from the Sun and takes 165 years to orbit it. A newly discovered dwarf planet is about 60 AU from the Sun.
(a)
Compare the orbit of the comet with the orbit of Earth.
[3 marks]
(b)
Predict whether the dwarf planet takes more or less than 165 years to orbit the Sun, and explain your prediction.
[4 marks]
Total for question 3: 7 marks
4
A school in Mumbai, India, is holding an astronomy week. Students make a model using a lamp, a polystyrene ball on a stick and a student's head to represent the Sun, the Moon and the Earth. The principal also asks them to debate whether India should keep spending public money on its space programme, which launches weather and navigation satellites and sends probes to the Moon.
(a)
Design an investigation using the model to find out how the phase of the Moon seen from Earth depends on the Moon's position in its orbit. Include a hypothesis with a reason, the variables, a method and one safety precaution.
[6 marks]
(b)
Discuss whether India should continue to spend public money on its space programme.
[6 marks]
Total for question 4: 12 marks
5
Astronomers in Hawaii observe a vast cloud of gas and dust in which a new star is forming. As the cloud collapses, its centre becomes denser and hotter, until the star begins to shine.
(a)
Which force pulls the gas and dust together to form the star?
[1 mark]
AGravity
BFriction
CAir resistance
DElectrostatic repulsion
(b)
Once the star shines steadily on the main sequence, why does it not collapse further?
[1 mark]
AGravity stops acting once the star has formed
BThe core cools until it becomes solid
CGravity from neighbouring stars pulls its outer layers outwards
DOutward pressure from fusion in the core balances the inward pull of its own gravity
(c)
State what happens to hydrogen nuclei in the core when the star begins to shine, and name the nuclei that are produced.
[2 marks]
Total for question 5: 4 marks
6
Sirius, the brightest star in the night sky as seen from Cairo, Egypt, is 8.6 light-years from Earth. One light-year is about $9.5 \times 10^{12}$ km.
(a)
What is a light-year?
[1 mark]
AA unit of time equal to one year
BThe distance from Earth to the Sun
CThe distance that light travels in one year
DThe speed of light in space
(b)
Which statement about the light from Sirius reaching a student in Cairo tonight is correct?
[1 mark]
AIt left Sirius 8.6 days ago
BIt left Sirius 8.6 years ago
CIt left Sirius $9.5 \times 10^{12}$ years ago
DIt left Sirius at the moment it reached Cairo
(c)
Calculate the distance from Earth to Sirius in kilometres. Give your answer to two significant figures.
[2 marks]
Total for question 6: 4 marks
7
A new space telescope in orbit around the Sun detects infrared light from a galaxy that is 13.4 billion light-years away. At the same time, astronomers using a large telescope on a mountain in the Canary Islands, Spain, struggle to observe the same galaxy.
(a)
Suggest three reasons why a telescope in space can give clearer images of distant galaxies than a telescope on the ground.
[3 marks]
(b)
Explain what the detection of light from this galaxy tells astronomers about the age of the Universe.
[4 marks]
Total for question 7: 7 marks
8
A company in the USA launches thousands of small satellites into low orbit, about 550 km above Earth, to give internet access to remote villages. Astronomers say the satellites leave bright streaks across images taken by telescopes. A student collects data on the time a satellite takes to orbit Earth at different heights: at 400 km the period is 92 minutes, at 1000 km it is 105 minutes and at 35 800 km it is 1440 minutes. The student's hypothesis is that the orbital period is directly proportional to the height above Earth.
(a)
Evaluate the student's hypothesis using the data.
[6 marks]
(b)
Discuss whether launching thousands of small satellites is justified, given the effect on astronomers' observations.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).