Question

The graph between the resistive force `F` acting on a body and the distance covered by the body is shown in the figure. The mass of the body is `25 kg` and initial velocity is `2 m//s`. When the distance covered by the body is `4m`, its kinetic energy would be

A. `50 J`
B. `40 J`
C. `20 J`
D. `10 J`

Answer 1

Initial `K.E.` of the body `= (1)/(2) mv^(2) = (1)/(2) xx 25 xx 4 = 50 J`
Work done against resistive force
` = Area between F-x graph`
`= (1)/(2) xx 4 xx 20 = 40 J`
Final `K.E. -` Work done against resistive force
`= 50 - 40 = 10 J`