Question

What is the work done by the force of gravity when a stone of mass is 250 g is thrown up through a height of 2.5 m?

Answer 1

In a given situation a stone is thrown upward and raised to a height of 2.5 m. In this case, the gravitational force is in a downward direction and displacement is in an upward direction. Now we can say displacement is in the opposite direction of the force.
We know that,

Gravitational force = F = mg

Mass, m = 250 g = 0.25 kg
Acceleration due to gravity. g = $9.8m/s^2$
Therefore, gravitational force = $F=0.25\times 9.8=2.45N$
Displacement = 2.5 m in the opposite direction of the force
Hence, Work done = $W=F.s=-2.45\times 2.5=-6.125J$
Thus, the total work done by gravity will be - 6.125 J.