Orbital motionEdexcel International A Level Physics: Mind map

Exam questions on Orbital motion

1. The International Space Station (ISS) moves in a circular orbit at a height of 4.0 × 10⁵ m above the Earth's surface. The Earth has mass 5.97 × 10²⁴ kg and radius 6.37 × 10⁶ m. G = 6.67 × 10⁻¹¹ N m² kg⁻².
   Calculate the time taken for the ISS to complete one orbit.2 marks
2. A geostationary communications satellite remains above the same point on the Earth's surface. The Earth has mass 5.97 × 10²⁴ kg and radius 6.37 × 10⁶ m, and it rotates once in 8.62 × 10⁴ s (one sidereal day). G = 6.67 × 10⁻¹¹ N m² kg⁻².
   Explain why a geostationary satellite must orbit in the plane of the equator.2 marks
3. Mars moves in an approximately circular orbit of radius 2.28 × 10¹¹ m around the Sun, which has mass 1.99 × 10³⁰ kg. G = 6.67 × 10⁻¹¹ N m² kg⁻². Take one year to be 3.16 × 10⁷ s.
   Show that the orbital period T of a planet in a circular orbit of radius r around the Sun is given by T² = 4π²r³/GM, where M is the mass of the Sun.3 marks