Question

A particle is projected up with a velocity of $\sqrt{29}{ms}^{-1}$ from the tower of height 10 m. What is its velocity on reaching the ground?

• A. $25{ms}^{-1}$
• B. $15{ms}^{-1}$
• C. $12.5{ms}^{-1}$
• D. $7.5{ms}^{-1}$

Answer 1

The correct option is B $15{ms}^{-1}$

Since body is under non conservative forces is Energy is conserved.

Initial Energy $=mg10+\frac{1}{2}m{v}^2=m98+m\left(\frac{29}{2}\right)=m.112.5$

Fnal enery $=\frac{1}{2}m{v}^2$

$\frac{1}{2}m{v}^2=m\times 112.5v^2=225v=15m/s$