Question 1

Newton’s law of gravitation states that the force between two point masses is proportional to which combination?

Accepted Answer

Product of the two masses and inversely proportional to the square of the distance. Gravitational force depends on m1×m2 and 1/r^2. This is the inverse square law of gravitation. It acts along the line joining the two masses.

Question 2

What is the dimensional formula of the universal gravitational constant G?

Accepted Answer

[M^-1 L^3 T^-2]. From F = G m1 m2 / r^2, G = Fr^2/(m1m2). So its dimensions are [M^-1 L^3 T^-2]. This remains the same in all unit systems.

Question 3

Which statement correctly relates mass and weight of a body near Earth?

Accepted Answer

Weight equals mg and changes if g changes. Weight is the gravitational force and equals mg. If g changes with place, weight changes too. Mass is the amount of matter and stays the same.

Question 4

The expression for escape velocity from the surface of a planet of mass M and radius R is?

Accepted Answer

sqrt(2GM/R). Escape velocity is the minimum speed to reach infinity with zero final speed. It is found by equating kinetic energy to gravitational potential energy change. The formula is v = sqrt(2GM/R).

Question 5

If h is small compared to Earth’s radius R, the acceleration due to gravity at height h is best approximated by?

Accepted Answer

g. Gravity decreases with altitude because distance from Earth’s center increases. For small h, g' ≈ g(1 - 2h/R). This comes from g' = g(R/(R+h))^2 using binomial approximation.

Gravitation — Set 1