A 23-lb crate is pushed by a force F, which has the magnitude that varies as shown on the graph. If the crate is originally at rest and it takes 3 seconds after applying the force to hit the bumper, determine:
1) The velocity of the crate just before it hits the bumper at A.
2) The maximum displacement of the plate A.
Neglect the mass of the bumper components and take: k1 = 500 lb/ft, k2 = 750 lb/ft, us = 0.5, uk = 0.4