Gravitation

Q1.Kepler's first law states that every planet moves in:

• Aa circular orbit around the Sun
• Ban elliptical orbit with the Sun at one focus
• Ca parabolic path around the Sun
• Da straight line through the Sun

Q2.The energy required to launch a satellite of mass m from Earth's surface to orbit at height h (R_E = R, neglect air resistance, g_0 at surface) is:

• AGMm h/R(R+h)
• Bmgh
• CGMm/(2(R+h))
• DGMm(2R+h)/(2R(R+h))

Q3.The orbital velocity of Earth around the Sun is approximately 30 km/s. The escape velocity from the Sun (at Earth's orbit) is approximately:

• A30 km/s
• B42.4 km/s
• C60 km/s
• D15 km/s

Q4.At depth d below Earth's surface, g is:

• Ag_0 (1 + d/R_E)
• Bg_0 (R_E - d)/R_E
• Cg_0 R_E^2/(R_E - d)^2
• Dg_0 d/R_E

Q5.The gravitational potential energy of a mass m at distance r from Earth's centre (Earth mass M) is:

• AGMm/r
• B-GMm/r
• CGMm/r^2
• D-GMm/r^2