Question

A body dropped from a height $h$ with initial velocity zero, strikes the ground with a velocity $3m/s$. Another body of same mass dropped from the same height $h$ with an initial velocity of $4m/s$. The final velocity of second mass, with which it strikes the ground is

• A. $5m/s$
• B. $12m/s$
• C. $3m/s$
• D. $4m/s$

Answer 1

The correct option is A $5m/s$

First body initial speed $u=0$

Final speed $=3m/s$

Second body initial speed$=4m/s$

Body is dropped from height $h$

So $a=g=10m/s^2$

$v^2=u^2+2gh$

$3^2=0+20h$

$9=20h$

$h=\frac{9}{20}$

Second object is also dropped from same height.

therefore, $h=\frac{20}{9}$

$u=4m/s$

$v^2=u^2+2gh$

$v=5m/s$