1. The problem statement, all variables and given/known data mass 1 is sitting on a frictionless table and is connected by a string to mass 2 which is hanging over the edge via pulley... 2. Relevant equations ∑F=ma 3. The attempt at a solution What is the normal force of mass 1 exerted on and exerted by? I think the normal force is exerted by the table and exerted on the mass. What is the tension in the string exerted on and exerted by? I think the tension in the string is exerted by mass 2 (hanging over the edge) and it's exerted on the string. What is the force of mg exerted on and exerted by? I think the force of mg would be exerted on the mass 1 and exerted by gravity. I understand forces pretty well, but I'm a little confused as to what exactly is exerting them and being exerted upon. Could someone tell me if i'm correct or wrong?