a) A lead screw is being used on a lathe machine to advance the carriage of the lathe in time with the rotation of the spindle. The screw has an effective diameter of 50 mm and a lead 5 mm. the screw must exert an axial thrust of 1.5 KN for driving the carriage. An effort of 100 N is required to create the movement. Calculate the operating efficiency of the lead screw.

A jackscrew is used to raise and lower a 100-kg block as shown in below figure. The screw has a pitch
P = 15 mm, mean radius r = 10 mm, and is single-threaded. The coefficient of static friction between
the screw and the supporting thread of the base is u = 0.25. Determine the operating efficiency of the
screw.