question_answer

A body of mass 2 kg is thrown vertically upwards with an initial velocity of 20 m/s. What will be its potential energy at the end of 2 s? (\[\text{g}=\text{1}0\text{ m}/{{\text{s}}^{\text{2}}}\])

Answer:

Given,   \[m=2\,\,kgu=20\,m/s\]                 \[t=2\,sg=10\,m/{{s}^{2}}\]                 \[P.E.=?\] We know, \[P.E.=mgh\] First we have to find ?h?. From the relation, \[S=ut+\frac{1}{2}g{{t}^{2}}\] We get, \[h=20\times 2-\frac{1}{2}\times 10\times {{(2)}^{2}}\]                 \[=40-20=20\,m\] \[\therefore \,\,P.E.=2\times 10\times 20=400\,J\]