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Q4. A screw jack is to be used to raise a casting of mass 1500 kg. The single start screw thread has a pitch of 2.5 mm. A force of 45 N is applied at right angles to a turning bar at a fixed radius of 600 mm to produce a constant rotational speed.

Calculate EACH of the following:

(a) the velocity ratio of the screw jack; (3)

(b) the efficiency of the screw jack lifting this casting; (5)

(c) the output work done per revolution; (3)

(d) the constant rotational speed, expressed in rpm, if the casting is lifted 150 mm in 12 seconds. (5)