1. The problem statement, all variables and given/known data See attachment. 2. Relevant equations (1) F=ma (2.13) W=ΔT (2.20) (weight) x (decrease in altitude of mass center of body) 3. The attempt at a solution I don't get where |v(t1)| and |v(t2)|^2 comes from. The book says |v(t1)| = 0, which I suppose is because initially there was no movement, so kinetic energy is 0? Does |v(t1)|=0 have anything to do with T=mgsinθ+mlθ'^2? Then it says |v(t2)|^2 = l^2θ'^2, and this totally confused me. First, why is v(t2) squared and not v(t1)? Second, obviously v(t2) is somehow related to T=mgsinθ+mlθ'^2, but I don't see how you get v(t2) from that. Also originally θ'^2 was already squared, so wouldn't |v(t2)|^2 = l^2θ'^4?? Very confused on this. Any help would be appreciated thanks.