Question1
A 70-g disk sits on a horizontally rotating turntable. The turntable makes 4 revolutions each second. The disk is placed 12cm from the axis of rotation of the turntable.
a. What is frictional force acting on the disk?
b. The disk will slide off turntable if it is located at a radius larger than 18 cm from the axis of rotation. What is the coefficient of static friction?
Question2
To store an energy produced in 1.0 hour by a 140 electric-power plant, how various cubic meters of water will have to be pumped from the lower to the upper reservoir? Suppose the upper reservoir is 470 above the lower and we can neglect the small change in depths within each. Water has a mass of 1000 for every.