Question

A man throws balls into the air one after another. He always throws a ball when the previous one thrown has just reached the highest point. The height to which each ball rises, if he throws 5 balls per second is $(g=10m{s}^{-2})$:

• A. 0.31 m
• B. 0.20 m
• C. 0.42 m
• D. 0.53 m

Answer 1

Answer: (B)

0.20 m

suppose $n-balls\to$

$finalvelocity,$ $v=0$

$u=0$

$T=\frac{1}{n}\sec$

$0=u-g\frac{1}{n}$

$\frac{g}{n}=u$

$v^2=u^2-2gh$

$0=\frac{g^2}{n^2}-2gh$

$\frac{g^2}{n^2}=2gh$

$h=\frac{g}{2n^2}$

$n=5$

$=\frac{10}{2\times 25}$

$=\frac{1}{5}m$