1. The 10-lb collar starts from rest at A and is lifted by applying a constant vertical force of F = 25 lb to the cord. If the rod is smooth, determine the power developed by the force at the instant u = 60°.
2. The 10-lb collar starts from rest at A and is lifted with a constant speed of 2 ft>s along the smooth rod. Determine the power developed by the force F at the instant shown.
3. The escalator steps move with a constant speed of 0.6 m>s. If the steps are 125 mm high and 250 mm in length, determine the power of a motor needed to lift an average mass of 150 kg per step. There are 32 steps.