1. The problem statement, all variables and given/known data In a cement mixer, cement, gravel, and water are mixed by tumbling in a slowly rotating drum. If the drum spins too fast, the materials stick to the wall instead of mixing. Assume the axis of rotation is horizontal. Calculate the maximum angular speed for which the materials will mix. Express the answer as the number of revolutions per minute. Radius = 0.68 m. 2. Relevant equations 3. The attempt at a solution I have tried using angular speed = v/r = theta/t . I assumed that t was equal to 1 minute and the angle was 2*pi. However, this did not work.