Calculate the gravitational force between a $10 \mathrm{kg}$ ball and a $20 \mathrm{kg}$ ball placed $5 \mathrm{m}$ apart from each other.

A ball is thrown up with a speed of $15 \mathrm{m}/\mathrm{s}$. How high will it go before it begins to fall?

(Choose from the following: $11.5 \mathrm{m}/ 12.5 \mathrm{m}/ 10.5 \mathrm{m}$)

 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?