3. A 1520 kg car is moving at 5.0 m/s east. The car then speeds up to 7.5 m/s east.
a) What is the impulse delivered to the car? (Ans: +3800 Ns)
b) If the engine provides a net force of 5.0 × 102 N, then how long does it take for the
impulse to be delivered? (Answer: 7.6 s)
4. A 256,000 kg train is moving at 45.0 m/s in the positive direction. What net force must be
applied to bring it to rest in 90.0 s? (Answer: -1.28 × 105 N)