I need help with a physics question 1. The problem statement, all variables and given/known data Figure shows 3 boxes with mass 50kg, 20kg & 30kg on a frictionless surface. 1. What is the horizontal force required to push the system with an acceleration of 1ms-1? 2. Find the Force exerted by 50kg on 20kg 3. Find the force exerted by 20kg on 30kg 2. Relevant equations 3. The attempt at a solution I was able to find the answer for the 1st question by using F=ma. And the answer i got was F=100N. But i dont know how to do question 2 & 3. So please help.