Question Detail

PHY 101 PHY 101 Past Questions Objective Question

Question

The time period T of a satellite orbiting the Earth in a circular orbit of radius r is given by:
Options
A T = 2π √(r/GM_E)
B T = 2π √(r³/GM_E)
C T = √(4π²r³/GM_E)
D Both B and C are equivalent.
Correct Answer
Correct Answer

Option D is the correct answer.

Detailed Explanation

From v = 2πr/T and v = √(GM_E/r), equating gives 2πr/T = √(GM_E/r). Squaring both sides: 4π²r²/T² = GM_E/r. Rearranging gives T² = (4π²/GM_E) r³, so T = 2π √(r³/GM_E). Option C is just the square root of that equation and is equivalent.

Hint

Combine the formulas for orbital speed and the circumference of the orbit.

Question Info