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Circular Motion and Gravitation — High School Physics practice questions

13 multiple-choice questions and 15 flashcards on Circular Motion and Gravitation, about 9% of the High School Physics bank. Every one carries a written rationale.

Written and maintained by the CoStudy team · last updated 2026-10-12 · how we write and review questions

What this chapter covers

Circular Motion and Gravitation is one of 11 chapters in CoStudy's High School Physics bank, and it holds 13 of the bank's 150 multiple-choice questions — roughly 9% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.

Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.

Free Circular Motion and Gravitation practice questions

7 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.

If one of two masses doubles, the gravitational force between them:

  1. doubles
  2. quadruples
  3. halves
  4. stays the same

Answer: A — doubles

A) Correct — F ∝ m₁m₂. B) Would require both masses to double. C) Gets the direction wrong. D) Force depends on mass.

Kepler's third law relates a planet's orbital period T to its average distance r by:

  1. T² ∝ r³
  2. T ∝ r
  3. T³ ∝ r²
  4. T ∝ 1/r

Answer: A — T² ∝ r³

A) Correct — Farther planets take much longer to orbit. B) Is too simple. C) Swaps the exponents. D) Gets the direction wrong.

A car turns on a flat road. What provides the centripetal force?

  1. Friction between the tires and road
  2. The car's engine
  3. Gravity
  4. Centrifugal force

Answer: A — Friction between the tires and road

A) Correct — Without friction the car would slide straight. B) Pushes forward, not inward. C) Acts downward. D) Is not a real force.

A 2 kg ball moves at 4 m/s in a circle of radius 2 m. What centripetal force is needed?

  1. 16 N
  2. 4 N
  3. 32 N
  4. 8 N

Answer: A — 16 N

A) Correct — F = mv²/r = 2 × 16/2. B) Uses mv/r. C) Leaves out dividing by r. D) Uses mv.

Kepler's first law states that planets orbit the Sun in:

  1. perfect circles centered on the Sun
  2. straight lines
  3. ellipses centered on the Sun
  4. ellipses with the Sun at one focus

Answer: D — ellipses with the Sun at one focus

D) Correct — Most planetary orbits are nearly circular ellipses. A) Orbits are ellipses. B) Gravity curves their paths. C) The Sun is at a focus, not the center.

At a distance of 2 Earth radii from Earth's center, the gravitational acceleration is about:

  1. g/4
  2. g/2
  3. 2g
  4. zero

Answer: A — g/4

A) Correct — g ∝ 1/r²; doubling r gives one-fourth. B) Treats g as ∝ 1/r. C) Gets the direction wrong. D) Gravity extends far into space.

If the distance between two masses doubles, the gravitational force between them becomes:

  1. half as large
  2. twice as large
  3. four times as large
  4. one-fourth as large

Answer: D — one-fourth as large

D) Correct — F ∝ 1/r². A) Treats F as ∝ 1/r. B) Gets the direction wrong. C) Inverts the relationship.

Circular Motion and Gravitation flashcards

4 cards from the 15 in this chapter.

What is centripetal force?

The net inward force required for circular motion: F_c = mv²/r. It is not a separate force but the net of real forces (gravity, tension, friction, etc.).

What is the period T of circular motion?

The time for one complete revolution.

What keeps planets in orbit around the Sun?

The gravitational force from the Sun, which acts as the centripetal force.

State Newton's Law of Universal Gravitation.

F = G m₁m₂ / r², where G ≈ 6.67×10⁻¹¹ N·m²/kg² is the gravitational constant.

Practise the full chapter

These are a sample. The full Circular Motion and Gravitation chapter runs 28 items with per-chapter progress tracking, on the web and in the iOS app.

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