Q. A body dropped from a height $h$ with an initial speed zero, strikes the ground with a velocity $3\ km/h$ . Another body of same mass is dropped from the same height $h\ $with an initial speed $–u^{\acute{\ }} = 4km/h$. Find the final velocity of second body with which it strikes the ground
A) $3\ km/h$
B) $4\ km/h$
C) $5\ km/h$
D) $12\ km/h$
Explanation
(c) For first case $v^{2} - 0^{2} = 2gh \Rightarrow (3)^{2} = 2gh$
For second case $v^{2} = ( - u)^{2} + 2gh = 4^{2} + 3^{2}\therefore v = 5km/h$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.