Hooke's Law States That the Force Required to Stretch or Compress

Multiple Choice

Hooke's law states that the force required to stretch or compress a spring to x units longer or shorter than its natural length is, for sufficiently small values of x, proportional to x. That is, F(x) = kx for some constant k, called the spring constant. Suppose that a force of 10 N is required to stretch a spring by 5 cm. Find the work done in stretching the spring that far.

A) 25 N . cm
B) 22 N . cm
C) 27 N . cm
D) 29 N . cm
E) 20 N . cm