1. a vehicle of mass 2.7 x 103 kg impacts an immovable test barrier and comes to a complete stop. a) if the sensors on the barrier indicate an impulse of 6.3 x 104 n-s for the crash, determine the initial velocity of the vehicle (in m/s and mi/h). b) if the crash lasts for 3.5 x 10-3 s, determine the average force (in n and lb) on the vehicle. 2. a ball is projected at an immovable wall with a speed vi and bounces back the wall in such a manner that it only has 1/3 of its original linear momentum. a) determine what fraction of the kinetic energy is lost in the collision. b) what happened to the kinetic energy that was lost?