When a rubber-band is stretched by a distance x

When a rubber-band is stretched by a distance x, it exerts a restoring force of magnitude F = ax + bx2 where a and b are constants. The work done in stretching the unstretched rubber band by L is

  1. aL2/2 + bL3/3
  2. (aL2 + bL3)/3
  3. aL2 + bL3
  4. (aL2/2 + bL3/3)/2

Answer

F = ax + bx2

dw = F dx

w = oL (ax + bx2)dx

w = aL2/2 + bL3/3

The correct option is A.