Question

A ball is thrown horizontally from the top of a $500\text{m}$ tall tower at $5\text{m/s}$. If another ball is thrown in a similar fashion after $2$ sec at $6\text{m/s}$, then how much time will the $2$nd ball take to reach the ground after the $1$st ball hits the ground.

• A. $1$ sec
• B. $3$ sec
• C. $0.5$ sec
• D. $2$ sec

Answer 1

The correct option is D $2$ sec

Both balls will take same time to reach the ground, making it independent of the initial velocity.
$t=\sqrt{\frac{2h}{g}}=\sqrt{\frac{2500}{10}}=10\text{sec}$
So once 1st ball hits the ground, 2nd ball will reach the ground after $2$ sec as it was thrown $2$ sec after the $1$st ball.