Year 12 Physics Space Practice Quiz 2 Solution
Data
rE
TJupiter
rJupiter
mJupiter
Sidereal period (day length) of Jupiter
mGanymede
/ 50
6380km
4332.589 Earth days
69911 km
1.8983x1027kg
9.9259 hours
1.4819 × 1023kg
1. What is the force on an object due to a gravitational field called? Multiple Choice: 1 mark each
a) Newton.
b) Weight.
c) Mass.
d) Torque.
2. What is the gravitational potential energy of a 700kg object in Jupiter orbit at an altitude of 10000km?
(−𝟏. 𝟏𝟏 × 𝟏𝟎𝟏𝟐 𝐉) 2 marks
3. What is the maximum amount of work that is done when a 2000kg satellite orbiting Jupiter falls from a
geostationary orbit to an orbit with an altitude of 30000km? (𝟗. 𝟓𝟐 × 𝟏𝟎𝟏𝟏 𝐉)
3 marks
4. A Low Earth Orbit satellite has a period of 120 minutes. What is its altitude?
5. Calculate the acceleration due to gravity on the surface of Jupiter.
(1690km)
(25.91 m.s-2)
2 marks
2 marks
6. What is the word used to describe a gain or loss of energy?
a) Heat.
b) Potential.
c) Power.
d) Work.
7. The escape velocity for Earth is about 11km/s. What does escape velocity mean?
a) The velocity of a rocket needed to reach the edge of the solar system.
b) The horizontal velocity needed to launch a projectile into orbit from a high mountain.
c) The velocity of a projectile at the surface needed to reach a distance of infinity.
d) The velocity needed to make it impossible to see your reflection in a mirror.
8. Explain why the vast majority of satellites orbit from west to east. (The Earth’s rotational motion is added to
satellite’s motion during launch if the satellite travels in a west-east direction, so orbiting in this direction
saves on fuel.)
1 mark
9. Explain how launching satellites close to the equator is beneficial. (The Earth’s rotational motion is added to
satellite’s motion during launch if the satellite travels in a west-east direction, so orbiting in this direction
saves on fuel. The velocity due to the Earth’s rotation is greatest at the equator, so the closer to the
equator a satellite is launched, the greater the fuel saving will be.)
2 marks
10. What does “g-force” mean?
a) A force caused by gravity.
b) Force per unit mass compared to the acceleration due to gravity.
c) It just means gravity.
d) The force experience by astronauts during launch.
11. Which statement about satellites is true?
a) The period of a satellite is independent of orbital velocity.
b) The Moon is in a geostationary orbit because it is visible from Earth each night.
c) Period depends on the mass of the satellite.
d) The greater the orbital distance, the longer the period.
12. What is the magnitude of the centripetal force acting on an 80000kg satellite in orbit around Jupiter at an
altitude of 200000km?
(139040N)
1 mark
13. A 15 kg object is swung in a horizontal circular path on an 80cm string. The string has a maximum tension of
60N. What is the maximum speed of the object? (1.79 m/s)
1 mark
14. Who did a thought experiment about launching satellites into orbit by shooting them horizontally?
a) Richard Feynman.
b) Isaac Newton.
c) Albert Einstein.
d) Jules Verne.
15. Why can’t the acceleration due to gravity (9.81 m.s-2 for Earth) be used in space?
a) There is no air in space.
b) There is zero gravity in space.
c) Astronauts experience weightlessness.
d) The Earth's gravity decreases with altitude.
16. Which principle allows the thrust (force) of rocket engines to be calculated?
a) Conservation of momentum.
b) Conservation of energy.
c) Conservation of mass.
d) Conservation of enthalpy.
17. The Jupiter-Sun distance is 778,500,000 km. Use Kepler's Law of Periods to estimate the mass of the
Sun. (1.993x1030kg)
2 marks
18. A marble travelling at a speed of 6.5 m/s rolls off a 1.8m high table. What is the range of the
marble? (3.9m). 2 marks
19. Which of the following has the greatest orbital period?
a) The Moon.
b) A geostationary satellite.
c) The International Space Station.
d) A Low Earth Orbit Satellite.
20. A soccer ball is kicked with a speed of 15m/s at an angle of elevation of 25o. What is the maximum
height of the soccer ball above the ground? (2.05m). 2 marks
21. What is responsible for orbital decay of LEO (Low Earth Orbit) satellites?
a) Running out of rocket fuel.
b) A decrease in the efficiency of their solar panels as they age.
c) Mass increase due to collecting space dust.
d) Air resistance.
22. Which famous experiment sought to detect the presence of the aether)? (Michelson-Morley experiment)
1 mark
23. What would be the fate of astronauts if they attempted to re-enter the Earth's atmosphere at too great an
angle (too close to perpendicular)? (Burn up)
1 mark
24. What would be the fate of astronauts if they attempted to re-enter the Earth's atmosphere at too small an
angle (too close to tangential)? (Bounce off / Never return to Earth / Freeze to death).1 mark
25. The distance between the centre of Jupiter and the centre of its moon Ganymede is 1070400km. What is the
distance from the centre of the Jupiter of the point of zero nett gravitational attraction along the line joining
the centres of the Jupiter and Ganymede? Neglect the gravitational effect of other bodies and the motion of
the Jupiter and the Ganymede. (1061025km). 2 marks
26. Define an inertial frame of reference. (A frame of reference that involves no acceleration). 1 mark
27. Einstein proposed a thought experiment where a person on a train travelling at the speed of light held a
mirror up to his face. Based on our current understanding of Physics, what would we expect to happen in
this thought experiment? (The person would see his reflection in the mirror.) 1 mark
28. How much energy must be supplied to accelerate a 2658kg object from rest to a quarter of the speed of
light? (7.72x1018J) 2 marks
29. A spacecraft travels from Earth to a distant star at a speed of 0.75c. The journey takes 10.82 years according
to on-board clocks. What is the distance to the star as measured by an observer on Earth? (12.27 light years
or 1.16x1017m) 2 marks
30. An alien race measures time in ligendas. A spacecraft travels from the alien's home planet to a distant star at
a speed of 0.93c. The journey takes 15.2 ligendas according to on-board clocks. What is the distance of the
journey as measured by an observer on the alien's planet? Hint: Measure distance in light ligendas. (38.5
light ligendas) 2 marks
31. A subatomic particle created in the upper atmosphere travels a distance of 437m in its own frame of
reference and 986m in an Earth frame of reference before decaying. How fast is it travelling? (0.896c or
2.69x108m/s) 2 marks
32. A blue car is twice as long as a red car when they are at rest. The cars pass a stationary policeman and the
policeman determines that the two cars have the same length. The red car is travelling at 80% of the speed
of light. How fast is the blue car travelling? (0.953939c or 2.862x108m/s) 3 marks
33. A rectangle of length 7.45m and height 2.92m measured at rest moves past a stationary observer
horizontally at high speed. How fast does it need to be travelling to be measured to be square by the
stationary observer? (0.91999c or 2.7600x108m/s) 2 marks