Question

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

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

Answer 1

The correct option is C $5$ m/s

Given initial velocity of 1st object$=0m/s$ and final velocity $=3m/s$

Initial velocity of 2nd object = $4m/s$ and final velocity $=xm/s$

Mass of 1st object= mass of 2nd object = $M$

and height of fall of object 1 = height of fall of object 2 = $h$

From equation of motion we get,

$v^2=u^2+2gs$ where $s=h=\frac{9}{2g}$

Thus

$v^2=16+2g\left(\frac{9}{2g}\right)$

$v=5m/s$