Q1: For lifting a load of 50 kg through a distance of 2.5 cm, an effort of 12.5 kg is moved through a distance of 40 cm. The efficiency of the lifting machine, is

ANS:D - 25%

Load = 50kg,
Effort = 12.5kg,
M.A = 50kg/12.5kg,
M.A = 500/125,
M.A = 4.
Now, V.R = distance moved by effort/distance moved by load.

V.R = 40/2.5,
V.R = 400/25 = 16.

Now, efficiency = M.A /V.RX 100 = 4/16X100 = 25%.
So option are not correct.