posted by puff puff .
A revolutionary cannon, with a mass of 2000kg, fires a 20kg ball horizontally. The cannonball has a speed of 140m/s after it has left the barrel. The cannon carriage is on a flat platform and is free to roll horizontally. What is the speed of the cannon immediately after it was fired? Answer in units of m/s.
Use the law of conservation of momentum. The total momentum of the cannon and the cannonball after firing is zero. Make sure the cannon and cannonball momenta have opposite signs when you solve the equation.