Velocity - time graph of a particle moving in a straight line is shown. Mass of particle is 2 kg. What is work done by all the forces on the particle in time interval between $t=0$ to $t=10s$ if velocity goes from $10 ms^{-1}$ to $-20 ms^{-1}$ ?

Question

a) 300 J b) -300 J c) 400 J d) -400 J