Question

A ball rolls off the top of stairway with a horizontal velocity of magnitude $1.8m/s$. The steps are $0.20m$ high and $0.20m$ wide. Which step will the ball hit first?

• A. First
• B. Second
• C. Third
• D. Fourth

Answer 1

The correct option is D Fourth

Ball rolls off the top of stairway. Horizontal velocity $u=1.8m/s$
Since the stairs have the same width as height, lets find the place where horizontal and vertical distance become equal .
$ut=\frac{g{t}^2}{2}$; $g=10m/s^2$
$t=\frac{2u}{g}=0.36$
Therefore horizontal distance covered $=ut=0.648$.

Thus the ball will reach in $0.648/0.2=3.24$ i.e the fourth step.