Question

If three objects of same mass are dropped from different heights $h_1$, $h_2$ & $h_3$ such that $h_1$ > $h_2$ < $h_3$, then which of the following is true about their corresponding potential energy ($P{E}_1$, $P{E}_2$ & $P{E}_3$):

• A. $P{E}_1$ > $P{E}_2$ > $P{E}_3$
• B. $P{E}_1$ > $P{E}_2$ < $P{E}_3$
• C. $P{E}_1$ < $P{E}_2$ < $P{E}_3$
• D. $P{E}_1$ < $P{E}_2$ > $P{E}_3$

Answer 1

The correct option is B

$P{E}_1$ > $P{E}_2$ < $P{E}_3$

Potential Energy $=$ Force $\times$ Displacement $=mg\times h$ where, $m$ is the mass, $g$ is acceleration due to gravity and $h$ is the height.

Since the objects are of the same mass and acceleration due to gravity has a fixed value on earth, the force $mg$ in all three cases are same.

$\Rightarrow$Potential Energy $=constant\times h$

$\Rightarrow$Potential energy is directly proportional to its height.

We know that, $h_1$ > $h_2$ < $h_3$.

Therefore, $P{E}_1$ > $P{E}_2$ < $P{E}_3$