1. The problem statement, all variables and given/known data Mass 1(2.0kg) sits on top of mass 2(5 kg), which rests on a frictionless surface. The coefficient of static friction between mass 1 and 2 is 0.30. A string of length 5.0m is tied to mass 2, and both masses are swung around in a horizontal circle. Calculate a) the max speed of the masses and b) the tension in the string. 2. Relevant equations Fc=mv^2/r 3. The attempt at a solution I got the correct answer to a) by assuming static friction was the centripetal force but I don't understand why it is. Wouldn't the direction of the static friction be perpendicular to the rope to oppose mass 1 from falling of mass 2 as they're swung? And for b) I don't know what to do because if I just use T as the centripetal force for mass 2 I don't have its mass so I cant calculate it.