Explain the working of an extension spring balance.

The mass of a plant is twice and its radius is three times that of the earth. The weight of a body, which has a mass of $5 kg$, on that planet will be

A body weighs $490 \mathrm{N}$ on a planet whose acceleration due to gravity is half of the earth. Calculate

a. the mass of the body.

b. the weight of the stone on the earth. (take $\mathrm{g}=9.8 \mathrm{m}/{\mathrm{s}}^2$)

A mass of $1 \mathrm{kg}$ is tied to a string as shown in the figure.

Find the force exerted on the mass by the Earth ($\mathrm{g}=9.8 \mathrm{m} {\mathrm{s}}^{-2}$).