Question

A ball of mass 2 kg is thrown up with a speed of 10 m/s. Fin the kinetic energy of the ball at the time of throwing .l Also find the potential enrgy of hte ball at the highest point. ( given g = 10 m/s.)

Answer 1

$$\begin{gathered} \mathrm{Kinetic}\mathrm{energy}\mathrm{at}\mathrm{the}\mathrm{time}\mathrm{of}\mathrm{throwing}: \\ \mathrm{KE}=\frac{1}{2}{\mathrm{mv}}^2 \\ =\frac{1}{2}\times 2\times {10}^2 \\ =100\mathrm{J} \\ \mathrm{From}\mathrm{the}\mathrm{law}\mathrm{of}\mathrm{conservation}\mathrm{of}\mathrm{energy},\mathrm{the}\mathrm{potential}\mathrm{energy}\mathrm{at}\mathrm{the}\mathrm{highest} \\ \mathrm{point}\mathrm{is}\mathrm{equal}\mathrm{to}\mathrm{kinetic}\mathrm{energy}\mathrm{at}\mathrm{the}\mathrm{lowest}\mathrm{point}. \\ \mathrm{Hence}, \\ \mathrm{Potential}\mathrm{energy}\mathrm{at}\mathrm{the}\mathrm{highest}\mathrm{point}=100\mathrm{J} \end{gathered}$$