Except, what if it's a ball rolling down an incline without slipping -- how does that change the velocity answer? And what would be different if it were a cylinder instead of a ball? We aren't given enough information by the OP to just say use 1/2mv^2.Hi fsm,
U need to know how to interpret graphs and the conservation of mechanical energy to do this. Ok, initially, the total energy of the particle is 5J. At point B, it has lost some P.E. and what's left is 2J. Some of the P.E. has been converted into K.E. which is 3J. U know the mass of the particle (500g). U can use the equation K.E. = 1/2 mv² and solve for v. Do the same for points C and D. U should get the answers pretty fast.
Hope that helps.