Universal Law of Gravitation - UNSOLVED PRACTICE SET
Chapter: Gravitation | Topic: Universal Law of Gravitation
UNIVERSAL LAW OF GRAVITATION - UNSOLVED PRACTICE SET
Topic: Universal Law of Gravitation
Multiple Choice Questions
Q1. According to Newton's Universal Law of Gravitation, the gravitational force between two objects depends on:
- Only their masses
- Only the distance between them
- Their masses and the distance between them
- Their velocities and temperatures
Q2. If the distance between two objects is doubled, keeping their masses constant, the gravitational force between them becomes:
- Double
- Half
- One-fourth
- Four times
Q3. Which of the following is the correct mathematical form of Newton's Law of Gravitation (where M and m are masses, r is distance, and G is the gravitational constant)?
- F = GMm / r
- F = GMm / r²
- GMm × r²
- G(M + m) / r²
Q4. Gravitational force between two objects acts along:
- A perpendicular direction to the line joining them
- The line joining the centres of the two objects
- A random direction
- The horizontal ground level only
Q5. Two balls of masses 2 kg and 4 kg are placed at a certain distance. The gravitational force on the 2 kg ball due to the 4 kg ball is F₁, and the force on the 4 kg ball due to the 2 kg ball is F₂. Which statement is correct?
- F₁ > F₂
- F₂ > F₁
- F₁ = F₂
- F₁ and F₂ are in the same direction
Q6. The gravitational force between the Earth and the Moon keeps the Moon in its orbit. This is an example of:
- Magnetic attraction
- Universal gravitation — the same force that makes apples fall from trees
- Nuclear force between large bodies
- Electrostatic force over large distances
Short Answer Questions
Q7. State Newton's Universal Law of Gravitation in your own words. What does 'universal' mean here?
Q8. You and your friend both experience gravitational force from the Earth. Why don't we feel the gravitational force between ourselves and other people around us in school?
Q9. If the mass of one of the two objects is doubled while everything else remains the same, what happens to the gravitational force? Show using the formula.
Q10. Newton was reportedly inspired by a falling apple. How does the falling of an apple relate to the motion of the Moon around the Earth? Write the key idea.
Q11. Does the Universal Law of Gravitation apply between objects on Earth only, or does it apply throughout the universe? Give one example to support your answer.
Q12. A student says: 'Gravitational force is a one-way force — the Earth pulls me but I don't pull the Earth.' Is this student correct? Explain.
Long Answer Questions
Q13. Explain Newton's Universal Law of Gravitation in detail. Write the formula, identify each symbol, and explain what happens to the force when:
(i) the masses are increased, and
(ii) the distance is tripled. Also mention one real-life application of this law.
Q14. Describe how Newton used the concept of gravitation to explain both the fall of objects on Earth and the revolution of the Moon around the Earth. What was the key insight that unified these two observations? How does this show the 'universality' of gravitation?
Q15. You are standing on the roof of your school building (about 10 metres high). A friend is standing below on the ground.
(i) Does the gravitational force on you change compared to when you are on the ground?
(ii) Explain using the formula F = GMm/r² and mention whether this change is significant.
(iii) In what real-life scenario does the change in gravitational force with distance become very significant?
Numerical / Application-Based Problems
Q16. Calculate the gravitational force between two cricket balls, each of mass 0.16 kg, placed 0.5 m apart. Comment on whether you could 'feel' this force if you were holding both balls.
Q17. The mass of the Earth is 6 × 10²⁴ kg and the mass of the Moon is 7.4 × 10²² kg. The average distance between the Earth and Moon is 3.8 × 10⁸ m. Calculate the gravitational force between them. What keeps the Moon moving in its orbit instead of falling straight to Earth?
Q18. Two objects have masses m and 3m, placed at a distance d apart. (i) Write the expression for gravitational force F₁ between them. (ii) If the distance is halved, find the new force F₂ in terms of F₁. (iii) By how many times does the force increase?