Question

The work done by a force F = ($-6x^3$)i N, in displacing a particle from x = 4 m to x = - 2 m is

• A. 360
• B. 240 J
• C. -240 J
• D. -360 J

Answer 1

Answer: (D)

-360 J

Answer 2

Work done = $\int F .dx$
Given
$F = -(6x^3 )iN$
$W=-\int ^4_{-2} 6x^3 dx$
$W=-6\left[\frac{x^4}{4}\right]^4_{-2}$
$W=-\frac{6}{4}[(4)^4-(-2)^4]$
$W=-\frac{6}{4}[256-16]$
W=-1.5 $\times$ 240 =-360 J