Question

The decrease in the potential energy of a ball of mass $20kg$which falls from a height of$50cm$ is

• A. $968J$
• B. $98J$
• C. $1980J$
• D. None of these

Answer 1

The correct option is B

$98J$

Step 1: Given

The mass of a ball $m=20kg$

The height $h=50cm=0.5m$

Step 2: Formula used

The decrease in the potential energy is,

$\Delta U=mgh$

where,$g=9.8m/s$

Step 3: Finding decrease in PE

Then, substitute the values in the formula,

$$\begin{gathered} \Delta U=20\times 9.8\times 0.5 \\ \Delta U=98J \end{gathered}$$

Therefore the decrease in the potential energy is $98J$.

Hence, the correct option is (B).