1. The problem statement, all variables and given/known data A horizontal 800.0 N merry-go-round with a radius of 1.5 m is started from rest by a constant horizontal force of 50.0 N applied tangentially to the merry-go- round. Find the kinetic energy of the merry-go-round after 3.0 s. Assume it is a solid cylinder. 2. Relevant equations KE = (1/2)(Iw^2) 3. The attempt at a solution Answer in the back is 280 J My answer, however, turns out to be 40ish. Here's how I did it: I found moment of inertia I of combined objects (I treated the forces as objects here): I = I_(mgr) + I_(object_at_edge) I = (.5MR^2) + (MR^2) I = (.5*80*1.5^2) + (5*1.5^2) I = 101.25 kg.m^2 Then, I chose the 50 N constant force as the force that maintains circular motion, so 50 = (mv^2)/r 50 = ((I/r^2)*v^2)/r 50 = ((101.25/1.5^2)*v^2)/1.5 v^2 = 1.667 v = 1.29 Now, KE = (.5)(Iw^2) = (.5)(101.25*(0.86)^2) = 43.5 J Haha, awfully messy.