Free Law of Universal Gravitation MCQs with Answers

1. According to Einstein, the gravity interaction is possible between

• A. Material object only
• B. Both material objects and electromagnetic radiation
• C. Electromagnetic radiations only
• D. none of these

Explanation: Reason: According to Einstein's general theory of relativity, gravity is not just a force between masses but is also the result of the curvature of spacetime caused by the presence of mass and energy, including

2. In the solar eclipse of 1919 A.D., bending of starlight was measured to be

• A. 1.745 degree
• B. 1.745 minutes
• C. 1.745 seconds
• D. 1.745 radians

Explanation: The bending of starlight during the solar eclipse of 1919 was measured to be approximately 1.745 degrees, supporting Einstein's theory of general relativity.

3. If OE is the angle of bending of light predicted by Einstein's theory of gravity and ON that by Newton's, then

• A. OE= ON
• B. OE= 0.5 ON
• C. OE =2ON
• D. No relation exists between OE and ON

Explanation: The angle of bending of light predicted by Einstein's theory is approximately double that predicted by Newton's theory. Therefore, OE = 2ON.

4. Which of the following is a property of a uniform gravitational field?

• A. Its magnitude is the same in all directions
• B. The gravitational potential has the same value at all points within it
• C. Its direction is opposite to the direction of motion of attest mass released in it
• D. Its field strength is the same at all points within it

Explanation: d) Its field strength is the same at all points within it:This option suggests that the field strength (magnitude of the gravitational field) is the same at all points within a uniform gravitational field. This is correct. In a uniform gravitational field, the field strength is constant throughout the field. The field strength determines the magnitude of the gravitational force experienced by an object in the field.

5. If by some phenomenon the Earth contracts to one half of its present size, then the value of gravitational potential energy becomes:

• A. Double
• B. One-half
• C. Remains the same
• D. Four times

Explanation: The formula for gravitational potential energy is U = -GMm/r Hence, U = 1/r. If r/2, then U = 1/(r/2). Therefore U = 2(1/r), the gravitational potential energy is doubled.

6. The SI unit of gravitational potential is :

• A. J/kg
• B. J/(m kg)
• C. J/(m s)
• D. Js

Explanation: The amount of work required to transport a body of unit mass from infinity to some point is known as gravitational potential. The mathematical expression will be G = W/m. The unit of work is joule and the unit of mass is the kilogram (kg), so the unit of gravitation potential will be J/Kg.

7. Choose the correct option.

• A. Newton discovered that gravity pulled everything away from it.
• B. None of these is correct.
• C. Both of these are correct
• D. Newton discovered that gravity pulls everything towards it.

Explanation: Gravity pulls everything towards it - this is a universal truth. Universal truths are always expressed in the present tense even when narration is in the past. Therefore, the correct sentence is "Newton discovered that gravity pulls everything towards it."

8. The atmosphere around the earth is held by:

• A. Clouds
• B. Winds
• C. Gravity
• D. None of these options are correct

Explanation: The atmosphere around the earth is held by gravitational force or gravity due to the earth. The earth's gravity attracts the atmosphere and keeps it bound. Hence, C is the correct option.

9. The ratio: gravitational force/electrostatic force between two electrons is always:

• A. Greater than unity
• B. Less than unity
• C. Equal to unity
• D. Zero

Explanation: Option A : Gravitational force / electrostatic force is not greater than unity. Option: B Electrostatic forces are much stronger than gravitational forces. This is because gravity depends on mass, atoms have tiny masses so the gravitational force between them is close to zero. Whereas, the electrostatic force related to charges is bigger. The ratio of gravitational force to electrostatic force is always less than 1.

10. What force provides the centripetal force for planets moving around the sun?

• A. Coulombs force
• B. Gravitational force
• C. Magnetic force
• D. None of these options are correct

Explanation: In the case of an orbiting planet, the force is gravity. The gravitational attraction of the Sun is an inward (centripetal) force acting on Earth. This force produces the centripetal acceleration of the orbital motion.