1. The problem statement, all variables and given/known data The two blocks in the figure are connected by a massless rope that passes over a pulley. The pulley is 12 cm in diameter and has a mass of 2.0 kg. As the pulley turns, friction at the axle exerts a torque of magnitude 0.55 N * m. If the blocks are released from rest, how long does it take the 4.0 kg block to reach the floor? 2. Relevant equations Taking mass 1 (m1) to be on the left, and mass 2 (m2) to be on the right: m1 = 4.0 kg m2 = 2.0 kg r = 0.06 m Mp = 2.0 kg f = 0.55 N * m a(m2) = -a(m1) T1 = m1 * a(m1) + m1 * g (T1 = Tension on mass 1) T2 = m2 * g - m2 * a(m1) (T2 = Tension on mass 2) Net Torque = T1 * r - T2 * r - f alpha = Net Torque / I I = 1/2 * Mp * r^2 (where Mp = Mass of Pulley) a(m1) = -alpha * r (negative acceleration and positive rotation) y = 1/2 * a * (delta)t^2 3. The attempt at a solution Using the above equations I get: Code (Text): alpha = 2*r(T1 - T2) - f ------------------ Mp * r^2 Substituting that alpha into the a(m1) = -alpha * r equation and then solving for a(m1), I get a(m1) = -2.14 m/s^2. Then substituting this value for acceleration into the above kinematic equation and solving for time, I get the time to be 0.97s, which is wrong. I'm not sure if my issue is just an issue of messing up the signs, or if I am approaching the problem wrong. Any help would be appreciated.