Question

A raindrop of mass $1g$ falling from a height of $1km$ hits the ground with a speed of $50m{s}^{-1}$. Which of the following statements is correct?
(Take $g=10m{s}^{-2})$.

• A. The loss of potential energy of the drop in $10J$
• B. The gain in kinetic energy of the drop is $1.25J$
• C. The gain in kinetic energy of the drop is not equal to the loss of potential energy of the drop
• D. All of these

Answer 1

The correct option is B The gain in kinetic energy of the drop is $1.25J$

$K.E$ at ground =loss of potential energy

$\frac{1}{2}m{v}^2$=loss of potential energy

$\frac{1}{2}\times 1\times {10}^{-3}\times {50}^2$=loss of potential energy

$\frac{1}{2}\times {10}^{-3}\times 2500$=loss of potential energy

$1.25j$ loss of potential energy=Gain of $K.E$