Question

A particle moves along the x – axis form x = 0 t x = 5m influence of force given by F = 7 – 2x + 3x2. Calculate the work done in doing so.

CLASS - XI PHYSICS (Work, Energy and Power)

Answer 1

F = (7 - 2x + 3x²) N
x = 0 to 5m

Work done = $\int\limits^5_0 {F} \, dx = \int\limits^5_0 {(7-2x+3 x^{2} )} \, dx$
⇒ W = [7(5-0) - (5²-0) + (5³-0)]
⇒ W = 35 - 25 + 125
⇒ W = 135J

Answer 2

Work done= integral F.Displacement

So, after integration u get

7x-x^2+x^3

Now substitute the values of x as5 and 0 respectively and subtract

U get 7*5-25+125-0

Ans= 135