Question

A body of mass $1kg$ is projected vertically up with certain velocity. At certain point its $P.E.$ and $K.E.$ are $8J$ and $90J$. Then maximum height reached by it is $(g=9.8m/s^2)$.

• A. $1m$
• B. $10m$
• C. $0.1m$
• D. $100m$

Answer 1

The correct option is B $10m$

Total mechanical energy at that point will be $TE=8J+90J=98J$

At topmost point the velocity will become $zero$ so only $P.E.$ will be there.

As $\text{the gravitational force is a CONSERVATIVE force so the mechanical energy will remain CONSERVED.}$

So the at the highest point the $PE=TE=98J$

If the highest point is at a height $h$ then the PE should be $mgh$

so the $h=\frac{98}{mg}=\frac{98}{1\times 9.8}=10meter$