20) If the screw is single-threaded, then lead of the screw is

21) Velocity ratio of a tool system is 500:1. If effort = 200N, then compression force in kN is

22) The mass of a railway wagon is 1000 kN. If the coefficient of friction between the wheels and the railway track is 0.0002, then the force required for displacement of the wagon is

23) Estimate the time to drill a hole of 20 mm dia, 80 cm depth in mild steel. Take cutting speed of 15 meter /minute and feed of 0.25 mm/revolution.

24) In lead-acid battery, electrode lead peroxide and lead immersed in electrolyte of diluted solution of sulphur acid having _____ percentage of concentration for full charge.