question_answer

A boy weighing 40 kg makes a high jump of 1.5 m. (i) What is his kinetic energy at the highest point?' (ii) What is his potential energy at the highest point?

Answer:

Given, \[m=40\,kgh=1.5\,m\] (i) At highest point K.E. = ? We know, \[K.E.=\frac{1}{2}m{{v}^{2}}\] But, at highest point velocity ?v? is zero \[\therefore K.E.=\frac{1}{2}\times m\times {{0}^{2}}=0\] (ii) At highest point P.E. = ? We know, \[P.E.=mgh\] \[\Rightarrow P.E.=40\times 9.8\times 1.5=588J\]