Why does an object float or sink when placed on the surface of water?

The earth and the moon are attracted to each other by gravitational force. Does the earth attract the moon with a force that is greater or smaller or the same as the force with which the moon attracts the earth? Why?

A ball is thrown vertically upwards with a velocity of $49\, m/s$. Calculate

$(i)$ the maximum height to which it rises,

$(ii)$ the total time it takes to return to the surface of the earth.

What is the magnitude of the gravitational force between the earth and a $1 \,kg$ object on its surface? (Mass of the earth is $6 \times 10^{24}\, kg$ and radius of the earth is $6.4 \times 10^6\, m$.)

Write the formula to find the magnitude of the gravitational force between the earth and an object on the surface of the earth.