While pushing off against the starting blocks at the beginning of a race, Olympic swimming great

Question

Michael Phelps generates a force that increases linearly from 0 N to 800 N over the first 0.30 s, and then
decreases steadily back to 0 N over the remaining 0.30 s (see the graph below showing the force versus time).
If his mass is 86 kg and he was initially at rest, what was his velocity at the instant he left the starting
blocks? (Hint: it is easiest to solve this problem using impulse-momentum.)