a 12g Bullet is fired into a block of wood with a speed of V equals 200 m/s. The block rests on a frictionless surface is attached to an ideal horizontal Spring that is a Spring constant of 200. The block with the invented bullet compressed the Spring a distance of 30 cmeters to the right before momentarily coming to a stop. Determine the mass of the wooden block​

You are traveling in a car going at a constant speed of 100km/h down a long, straight highway. you pass another car going in the same direction which is traveling at a constant speed of 80km/h. as measured from your car's reference frame this other car is traveling at −20km/h. what is the acceleration of your car as measured from the other car's reference frame? what is the acceleration of the other car as measured from your car's reference frame?