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

Answer 1

Answer: (A)

Initial velocity of first body $(u_1)=0;$
Final velocity $(v_1)=3m/s$ and initial velocity of
second body $(u_2)=4m/s$
height $(h)=\frac{v_1^2}{2g}=\frac{(3{)}^2}{2\times 9.8}=0.46m.$
Therefore velocity of the second body,
$V_2=\sqrt{u_1^2+2gh}=\sqrt{(4{)}^2+2\times 9.8\times 0.46}=5m/s.$