Ablue train of mass 50 kg moves at 4 m/s toward a green train of 30 kg initially at rest. the trains collide. after the collision the green train moves with a speed of 3 m/s. what is the final momentum of the blue and green train combined?
a. 90 kgm/s
b. 110 kgm/s
c. 50 kgm/s
d. 200 kgm/s

One hazard of space travel is debris left by previous missions. there are several thousand masses large enough to detect by radar orbiting the earth, but there are far greater numbers of very small masses such as flakes of paint. calculate the force exerted by a 0.110 mg chip of paint that strikes a space shuttle window at a relative speed of 5.00 ✕ 103 m/s and sticks, given the collision lasts 6.00 ✕ 10-8 s. such a collision chipped the window of the ill-fated challenger in june 1983, causing $50,000 of damage.