Question

A position dependent force, F = (7 – 2x + 3x²) N
acts on a small body of mass 2 kg and displaces it
from x = 0 to x = 5 m. Work done in joule is
(a) 35 (b) 70
(c) 135 (d) 270

Answer 1

work done = F. S ,. where. S is the displacement.

dw = F.ds

on integrating both the side

w= integration of F.ds

= integration of ( 7-2x+3x^2) dx

= 7x - x^2+ x^3

by putting the limits , from 0 to 5

w= 7×5 -5^2+5^3

w= 35-25 +125

w= 135 joule