The Gravitational Constant G - UNSOLVED PRACTICE SET
Chapter: Gravitation | Topic: Gravitational Constant G
THE GRAVITATIONAL CONSTANT G - UNSOLVED PRACTICE SET
Topic: Gravitational Constant G
Multiple Choice Questions
Q1. The SI unit of the Universal Gravitational Constant G is:
- N m kg⁻²
- N m² kg⁻²
- N m² kg⁻¹
- N kg² m⁻²
Q2. The value of G is approximately:
- 6.674 × 10⁻¹¹ N m² kg⁻²
- 9.8 m/s²
- 6.674 × 10¹¹ N m² kg⁻²
- 6.674 × 10⁻⁸ N m² kg⁻²
Q3. Who was the first scientist to experimentally determine the value of G?
- Isaac Newton
- Galileo Galilei
- Henry Cavendish
- Albert Einstein
Q4. The very small value of G (6.674 × 10⁻¹¹ N m² kg⁻²) tells us that:
- Gravity is the strongest force in nature
- Gravitational force between everyday objects is extremely weak
- G changes with temperature
- Only large planets experience gravity
Q5. Which property of G makes it a 'universal' constant?
- Its value changes on the Moon
- It is different for different materials
- It remains the same everywhere in the universe regardless of the type of matter
- It only applies on Earth
Q6. In the formula F = GMm/r², if G were ten times larger (all else unchanged), the gravitational force between two objects would be:
- Ten times smaller
- Ten times larger
- Hundred times larger
- Unchanged
Short Answer Questions
Q7. What is the gravitational constant G? How is it different from the acceleration due to gravity 'g'? Give one key difference.
Q8. Cavendish used a torsion balance to measure G. Why was his experiment considered so challenging and significant for science?
Q9. Why is G called a 'universal' constant? Does it change if you go from Earth to Mars?
Q10. From the formula F = GMm/r², isolate (derive the expression for) G. Also write its SI unit.
Q11. A student confuses G with g. Write two clear sentences that distinguish between these two quantities for this student.
Q12. The gravitational force between a pencil (10 g) and an eraser (5 g) placed 5 cm apart on your desk is tiny. Why do these objects not move toward each other despite this force?
Long Answer Questions
Q13. Explain the significance of the universal gravitational constant G. Include:
(i) its numerical value and unit,
(ii) what its small value implies about gravitational force in everyday life,
(iii) why it is called 'universal', and
(iv) who first measured it and how (brief description).
Q14. Compare and contrast G (universal gravitational constant) and g (acceleration due to gravity). Your answer must include:
(i) what each represents physically,
(ii) numerical values and units,
(iii) whether each is constant everywhere, and
(iv) how they are related through the formula g = GM/R².
Q15. Imagine you are a scientist in the 1790s tasked with finding the value of G. Describe the challenges you would face and the logic behind measuring it. How does knowing G help us 'weigh' the Earth? Explain the method of finding Earth's mass once G is known.
Numerical / Application-Based Problems
Q16. Two iron spheres, each of mass 20 kg, are kept with their centres 2 m apart in a physics lab.
(i) Calculate the gravitational force between them.
(ii) Would you expect this force to move the spheres visibly? Justify.
Q17. Using the formula g = GM/R², calculate the value of g at Earth's surface. Given: Mass of Earth M = 6 × 10²⁴ kg, Radius of Earth R = 6.4 × 10⁶ m, G = 6.674 × 10⁻¹¹ N m² kg⁻².
Q18. A student wants to calculate the mass of the Moon using G. Given: Gravitational force between Earth and Moon F = 2.0 × 10²⁰ N, mass of Earth M = 6 × 10²⁴ kg, distance between them r = 3.8 × 10⁸ m, G = 6.674 × 10⁻¹¹ N m² kg⁻². Calculate the mass of the Moon.