Question

A body of mass 250g is dropped from height of 100m find its potential energy and kinetic energy after 3sec

Answer 1

748 J is its potential energy and kinetic energy after 3 second

Answer 2

Answer:

Potential energy of the body after 3 s, PE = 136.955 J

Kinetic energy of the body after 3 s, KE = 108.045 J

Explanation:

Given that,

           Mass of the body = 250g

            height, h = 100m

The distance travelled by the body in 3 seconds ,

                                                                     $S=\frac{1}{2}gt^2$

                                                                     $S=\frac{1}{2}\times 9\cdot 8\times 3^2=44\cdot 1 m$

Velocity of the body after 3 s , v = gt = 9.8 $\times$ 3 = 29.4 m/s

Potential energy of the body after 3 s, PE = mg(h-s)

                                                                $\begin{aligned}PE=250\times 10^{-3}\times 9\cdot 8\times \left(100-44\cdot 1\right)\\=136.955 J\end{aligned}$

Kinetic energy of the body after 3 s, KE = $\frac{1}{2}\times m \times v^{2}$

                                                             $\begin{aligned}KE=\frac{1}{2}\times 250\times 10^{-3}\times 29\cdot 4^2\\=108.045 J\end{aligned}$