A machine part consists of a thin 40.0-cm-Iong bar with small l.15-kg masses fastened by screws to its ends. The screws can support a maximum force of 75.0 N without pulling out. This bar rotates about an axis perpendicular to it at its center.
(a) As the bar is turning at a constant rate on a horizontal frictionless surface, what is the maximum speed the masses can have without pulling out the screws?
(b) Suppose the machine is redesigned so that the bar turns at a constant rate in a vertical circle. Will one of the screws be more likely to pullout when the mass is at the top of the circle or at the bottom? Use a free-body diagram to see why.
(c) Using the result of part (b), what is the greatest speed the masses can have without pulling a screw?