1. The problem statement, all variables and given/known data A projectile launcher fires a projectile horizontally from a platform which rests on a flat, icy, frictionless surface. Just after the projectile is fired and while it is moving through the launcher, the projectile has an accelleration of 25m/s^2. At the same time, the launcher has an accelleration of 0.25m/s^2. The mass of the projectile is 0.20kg. Calculate the mass of the launcher. Given: acceleration of projectile: 25m/s^2[forwards]. Accelleration of launcher: 0.25m/s^2[backwards]. mass of projectile- 0.20kg 2. Relevant equations Fnet=ma 3. The attempt at a solution I have no clue how to solve this. I checked the solution, and according to that, you have to solve for Fnet of the projectile using Fnet=ma, and the net force of the launcher is equal in magnitude but opposite in direction to that of the projectile. Then you use Fnet=ma for the launcher and solve for mass. I don't understand why the net force of the launcher is equal in magnitude but opposite in direction to that of the launcher. Can someone explain?