Question

A stone is thrown vertically upwards with an initial velocity of $25\text{m/s}$. The maximum height reached by the stone is
$[$Take $g=10{\text{m/s}}^2]$

• A. $11.5\text{m}$
• B. $20.15\text{m}$
• C. $31.25\text{m}$
• D. $5.75\text{m}$

Answer 1

The correct option is C $31.25\text{m}$

When the stone reaches the highest point, its velocity becomes zero.
$\Rightarrow v=0$
Also,
$u=25\text{m/s}$ and
$a=-g=-10{\text{m/s}}^2$
Applying, $v^2=u^2+2as$
$\Rightarrow 0^2=(25{)}^2+2\times (-10)\times s$
or, $s=\frac{25\times 25}{20}\Rightarrow s=31.25\text{m}$