The universal law of gravitation was given by Isaac Newton and G is 6.67 × 10⁻¹¹ N m²/kg², so this Class 9 sheet opens with the law's author and its constant. The key also fixes g at 9.8 m/s² and the acceleration in free fall through it.
Key Takeaways
Newton gave the universal law of gravitation (Q1).
G = 6.67 × 10⁻¹¹ N m²/kg² (Q2).
Q3 records g = 9.8 m/s².
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.The universal law of gravitation was given by
(a) Galileo Galilei(b) Isaac Newton(c) Albert Einstein(d) Johannes Kepler
2.The value of the universal gravitational constant G is
(a) 6.67 × 10⁻¹¹ N m²/kg²(b) 6.67 × 10¹¹ N m²/kg²(c) 9.8 N m²/kg²(d) 6.67 × 10⁻⁷ N m²/kg²
3.The acceleration due to gravity on the surface of the Earth is about
(a) 9.8 m/s(b) 9.8 m/s²(c) 6.67 m/s²(d) 980 m/s²
4.The value of acceleration due to gravity at the centre of the Earth is
(a) 9.8 m/s²(b) zero(c) maximum(d) half its surface value
5.The weight of a body is
(a) its mass(b) the force with which the Earth attracts it(c) the same everywhere(d) measured in kilograms
6.The mass of a body
(a) changes from place to place(b) remains the same everywhere(c) becomes zero on the Moon(d) is more at the poles
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.State the universal law of gravitation.
8.Why is G called a universal constant?
9.Define acceleration due to gravity. What is its value on the surface of the Earth?
10.Why does a body weigh slightly more at the poles than at the equator?
11.What is the difference between mass and weight?
12.Why do the planets keep revolving around the Sun without falling into it?
13.State the relation between g and G for a body on the surface of the Earth.
14.Why is the weight of a body on the Moon about one-sixth of its weight on the Earth?
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.Two bodies of masses 60 kg and 40 kg are kept at a distance of 2 m from each other. Calculate the force of gravitation between them. (G = 6.67 × 10⁻¹¹ N m²/kg², use F = G m₁m₂ ÷ d²)
16.A body of mass 5 kg is falling freely under gravity. Find the force of gravity acting on it. (g = 10 m/s², F = mg)
17.A ball is thrown vertically upward with a velocity of 30 m/s. Find the maximum height reached and the total time of flight. (g = 10 m/s², use v² = u² - 2gh and v = u - gt)
18.An object of mass 30 kg is taken to the Moon. Find its weight on the Earth and on the Moon. (g = 10 m/s², weight on the Moon = 1/6 of the weight on the Earth)
19.A body weighs 60 N on the surface of the Earth. Find its mass. (g = 10 m/s², m = W ÷ g)
20.A stone is dropped from a cliff and reaches the ground in 3 seconds. Find the height of the cliff. (g = 10 m/s², use h = ½gt²)
Answer Key
1. b) Isaac Newton
2. a) 6.67 × 10⁻¹¹ N m²/kg²
3. b) 9.8 m/s²
4. b) zero
5. b) the force with which the Earth attracts it
6. b) remains the same everywhere
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
10. Refer to solution guide.
11. Refer to solution guide.
12. Refer to solution guide.
13. Refer to solution guide.
14. Refer to solution guide.
15. Refer to solution guide.
16. Refer to solution guide.
17. Refer to solution guide.
18. Refer to solution guide.
19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
Who gave the universal law of gravitation?
Isaac Newton, option (b) in this worksheet (Q1).
What is the value of G?
6.67 × 10⁻¹¹ N m²/kg², option (a) in this worksheet (Q2).
What is the value of g on Earth?
9.8 m/s², option (b) in this worksheet (Q3).
Stuck on a similar problem? Clear your next doubt instantly with the Doubt Solver.
Browse more free worksheets for CBSE Grade 9.