posted by Renee .
A cannon on a railroad car is facing in a direction parallel to the tracks (the figure below ). It fires a 99-kg shell at a speed of 105 m/s (relative to the ground) at an angle of 60 above the horizontal. If the cannon plus car have a mass of 4.6 104 kg, what is the recoil speed of the car if it was at rest before the cannon was fired?
change athe speed of the shell to horizontal speed, then use the conservation of momentum principle.