A bullet of mass 20 g, travelling at a speed of 350 ms-1, strikes a steel plate at an angle of 30º with the plane of the plate. It ricochets off at the same angle, at a speed of 320 ms-1. What is the magnitude of the impulse that the steel plate gives to the projectile? If the collision with the plate takes place over a time ∆t = 10-3 s, what is the average force exerted by the plate on the bullet?