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Question

Physics Question on work, energy and power

A particle moves along the xx-axis from x=x1x=x_{1} to x=x2x=x_{2} under the action of a force given by F=2xF=2 x. Then the work done in the process is

A

zero

B

x22x12x_{2}^{2}-x_{1}^{2}

C

2x2(x2x1)2 x_{2}\left(x_{2}-x_{1}\right)

D

2x1(x1x2)2 x_{1}\left(x_{1}-x_{2}\right)

Answer

x22x12x_{2}^{2}-x_{1}^{2}

Explanation

Solution

Mechanical work (W)(W) is the force applied through a distance, defined mathematically as the line integral of a scalar product of force (F)(F) and displacement (dx)(d x) vectors
W=FdxW=\int F d x
Given F=2xF=2 x
hence W=x1x22xdxW=\int\limits_{x_{1}}^{x_{2}} 2 x d x
=2[x22]x1x2=2\left[\frac{x^{2}}{2}\right]_{x_{1}}^{x_{2}} =x22x12=x_{2}^{2}-x_{1}^{2}