Question

A ball is thrown vertically upwards with a velocity of $10m{s}^{-}1$. it returns to the ground with a velocity of $9m{s}^{-}1$. if $g=9.8m{s}^{-}2,$, the maximum height attained by the ball is nearly

• A. $5.1m$
• B. $4.1m$
• C. $4.61m$
• D. $5m$

Answer 1

The correct option is A $5.1m$

Given,

$u=10m/s$

$v=0m/s$

$g=9.8m/s^2$

Lets consider $H=$ maximum height attained by the ball

From 2nd equation of motion,

$2as=v^2-u^2$

$-2gH=v^2-u^2$

$H=\frac{v^2-u^2}{-2g}$

$H=\frac{0^2-10\times 10}{-2\times 9.8}=\frac{-100}{-19.6}$

$H=5.1m$

The correct option is A.