A particle of mass m initially at rest. A variabl force acts on the particle `f=kx^(2)` where k is a constant and x is the displacment. Find the work done by the force f when the speed of particles is v.
A. `1/2kx^(2)`
B. `1/2kv^(2)`
C. `1/2mv^(2)`
D. `2mv^(2)`