Question

a force F=3X²+2x-7 N acts on a 2kg body as a resut of which the body gets displaced from x=0 tox=5 .find the work done by the force

Answer 1

as Force is a function of x, then workdone will be got only by integration method

So (7 - 2 x + 3 x2 ) dx for limits 3 to 7

Integrating we get 7 x - 2 x2/2 + 3x3/3

After cancelling 2 and 3 in second and third terms we hae 7x - x2 + x3

With upper limit x = 7, we have 49 - 49 + 343 = 343

With lower limit x = 3 we have 21 - 9 + 27 = 39

Henc work done = 343 - 39 = 304 J