Question

A stone dropped from a cliff on the surface of the Moon, reaches the surface of the moon in $30s$. If the acceleration due to gravity of the Moon is $1.63m{s}^{-2}$, calculate the velocity of the stone on touching the surface of the Moon?

Answer 1

Step 1: Given data

Initial velocity of stone, $u=0$

Time taken, $t=30s$

Acceleration due to gravity, $g=1.63m{s}^{-2}$

Final velocity of the stone, $v=?$ (To be calculated)

Step 2: Calculating the final velocity of the stone

Applying the equation of motion for the freely falling object,

$$\begin{gathered} v=u+gt \\ \Rightarrow v=0+1.63m{s}^{-2}\times 30s \\ \Rightarrow v=48.9m{s}^{-1} \end{gathered}$$ [ '$g$' is positive when a body falls downwards]

Hence, the final velocity of the stone is $48.9m{s}^{-1}$.