Key Concepts: The universe contains billions of galaxies, each with billions of stars. Orbits are caused by gravity. Stars change over time depending on mass.
Section A: Units
1. State the SI units for mass, distance, speed, acceleration, force, time and gravitational field strength. [7]
Section B: Motion in the Universe
2. State what a galaxy is and where our solar system is located. [2]
3. Explain why gravitational field strength varies on different planets and on the Moon. [3]
Section C: Orbits
4. Explain how gravity causes moons, planets and satellites to orbit. [3]
5. Describe differences in orbits of comets, moons and planets. [3]
6. Calculate orbital speed for a satellite with radius $r = 7.0 \times 10^6\,m$ and period $T = 6000\,s$. [2]
Section D: Stellar Evolution
7. Explain how star colour relates to temperature and classify red and blue stars. [2]
8. Describe the life cycle of a Sun-like star. [4]
9. Describe the evolution of a star more massive than the Sun. [4]
Total marks: 27
Mark Scheme
1. kg, m, m/s, $m/s^2$, N, s, N/kg [7]
2. Galaxy: collection of billions of stars; solar system is in the Milky Way [2]
3. g depends on mass and radius of planet; Moon has smaller mass so lower g [3]
4. Gravity provides centripetal force for orbiting objects (moons/planets/satellites/comets) [3]
5. Comets have highly elliptical orbits; planets nearly circular; moons orbit planets [3]
6. $v = 2\pi r/T = 2\pi(7.0 \times 10^6)/6000$ about $7.3 \times 10^3\,m/s$ [2]
7. Blue stars are hotter; red stars are cooler [2]
8. Nebula -> main sequence -> red giant -> white dwarf [4]
9. Nebula -> massive main sequence -> red supergiant -> supernova -> neutron star/black hole [4]