AP Physics C: Mechanics 2.6.A Gravitational Interactions

Practise AP Physics C: Mechanics 2.6.A by applying inverse-square gravitation to masses and distances, comparing gravitational fields, and explaining free-fall acceleration.

Exam points

Apply F = GMm/r² to calculate force ratios from masses and centre-to-centre distances.
Use g = GM/r² to compare surface gravity and explain equal free-fall acceleration in a vacuum.

[Maximum number: 1]

Two moons of equal mass are in circular orbits around a planet. Moon 1 orbits with a radius of r and moon 2 orbits with a radius of 3 r. What is the ratio of the magnitude of the planet's gravitational force on moon 2 to that on moon 1, $F_{G(\text { on } 2)} / F_{G(\text { on } 1)}$ ?

9/1

3/1

1/1

1/3

1/9

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2.6.A—Describe the gravitational interaction between two objects or systems with mass question 1