If a man weighs $60 \mathrm{kg}$ on earth, how far must he go from the centre of the earth so that he weighs $30 \mathrm{kg}$? (Radius of earth $= 6400 \mathrm{km}$)

 A paperweight thrown upwards attains a maximum height of $19.6 \mathrm{m}$. Find the velocity $\left(\mathrm{in} {\mathrm{ms}}^{-1}\right)$ with which it was thrown. (Acceleration due to gravity $9.8 {\mathrm{ms}}^{-2}$)

(choose the answer from: $19.6 / 384.16$)

A ball thrown upwards attains a maximum height in $5 \mathrm{s}$. Find the velocity with which it was thrown?

(Choose from the following: $49 \mathrm{m}/\mathrm{s}, 4.9 \mathrm{m}/\mathrm{s}, 98 \mathrm{m}/\mathrm{s}, 9.8 \mathrm{m}/\mathrm{s}$)

Calculate the force of attraction (in newton) between the car (mass $=1000 \mathrm{kg}$) and the earth. Given mass of the earth $=6\times {10}^{24} \mathrm{kg}$; radius of the earth $=6.4\times {10}^6 \mathrm{m}$; $G=6.67\times {10}^{-11} \mathrm{N} {\mathrm{m}}^2 {\mathrm{kg}}^{-2}$.

(Choose from $9770.5 / 0.0015$)

What happens to the gravitational force between two objects when the distance between them is (a) doubled (b) halved? 

Explain how Newton's law of gravitation and Newton's third law of motion are similar.

 State Newton's law of gravitation. Get the expression of force.

Find the value of acceleration due to gravity on the surface of the moon in $\left({\mathrm{ms}}^{-2}\right)$. Mass of the moon = $7.35\times {10}^{22} \mathrm{kg}$, Radius of the moon = $1.74\times {10}^6 \mathrm{m}$, G = $6.67\times {10}^{-11}{\mathrm{Nm}}^2{\mathrm{kg}}^{-2}$.