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Quiz Chapter 3: Gravitation

10 questions · Form 4 Physics Bab 3: Gravitation

Question 1 of 10Score: 0

Which formula correctly gives the escape velocity, v_e, from the surface of Earth with mass M and radius R?

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. Which formula correctly gives the escape velocity, v_e, from the surface of Earth with mass M and radius R?

  1. v_e = √(GM / R)
  2. v_e = √(2GM / R)
  3. v_e = 2GM / R²
  4. v_e = √(GM / 2R)
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Answer: B

Escape velocity is derived by equating initial kinetic energy to gravitational potential energy, yielding v_e = √(2GM / R).

2. Which type of satellite remains stationary over the same point on Earth's equator at all times?

  1. Polar orbit satellite
  2. Low Earth orbit satellite
  3. Non-geostationary satellite
  4. Geostationary satellite
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Answer: D

A geostationary satellite orbits directly above the equator with a 24-hour period, keeping it fixed relative to Earth's surface.

3. Which factor does NOT affect the escape velocity of an object from a planet's surface?

  1. Mass of the planet
  2. Universal gravitational constant
  3. Mass of the launched object
  4. Radius of the planet
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Answer: C

The formula v_e = √(2GM / R) depends on G, planetary mass M, and planetary radius R. It is independent of the mass of the escaping object.

4. Which of Kepler's laws states that a planet sweeps out equal areas in equal intervals of time?

  1. Kepler's First Law
  2. Kepler's Third Law
  3. Kepler's Second Law
  4. Newton's First Law
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Answer: C

Kepler's Second Law (Law of Areas) states that a line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.

5. What is the relation between linear speed v and orbital distance r for a satellite in a circular orbit?

  1. v is directly proportional to r
  2. v is directly proportional to √r
  3. v is inversely proportional to r²
  4. v is inversely proportional to √r
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Answer: D

From v = √(GM / r), the linear orbital velocity v is inversely proportional to the square root of radius r (v ∝ 1/√r).

6. Two objects of mass 50 kg and 80 kg are placed 2 m apart. Calculate the gravitational force between them. (G = 6.67 × 10-11 N m² kg-2

  1. 6.67 × 10-8 N
  2. 1.33 × 10-7 N
  3. 6.67 × 10-9 N
  4. 2.67 × 10-8 N
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Answer: A

F = G(m1)m2r² = 6.67 × 10-11 × 50 × 802² = 2.668 × 10-74 = 6.67 × 10-8 N.

7. Calculated from Earth's surface (M = 5.97 × 1024 kg, R = 6.37 × 106 m, G = 6.67 × 10-11 N m² kg-2, what is Earth's approximate escape velocity?

  1. 7.9 km s-1
  2. 11.2 km s-1
  3. 15.0 km s-1
  4. 9.8 km s-1
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Answer: B

v_e = √[2 × 6.67 × 10-11 × 5.97 × 10246.37 × 106] ≈ 11,180 m s-1 ≈ 11.2 km s-1.

8. What is the main application of non-geostationary satellites like TiungSAT and RazakSAT?

  1. Direct-to-home satellite TV broadcast
  2. Earth observation and environmental sensing
  3. 24-hour fixed communications link
  4. Geostationary weather monitoring
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Answer: B

Non-geostationary satellites in lower orbits sweep across different geographical zones, making them ideal for high-resolution Earth imaging and sensing.

9. A body of mass 2 kg moves in a circle of radius 0.5 m at a constant speed of 4 m s-1. What is the centripetal force required?

  1. 16 N
  2. 64 N
  3. 32 N
  4. 8 N
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Answer: C

F_c = m v² / r = 2 × 4²0.5 = 2 × 160.5 = 642 = 32 N.

10. If Earth's radius is R, at what height h above Earth's surface is gravitational acceleration equal to g4?

  1. h = R
  2. h = 2R
  3. h = 0.5R
  4. h = 4R
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Answer: A

g ∝ 1r². For g' = g4, the total radius from Earth's centre must double to 2R. Thus r = R + h = 2R => h = R.

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