Question

A simple wheel and axle is used to lift a bucket of water from a well the radii of the wheel and axle are 20cm and 4cm respectively determine the theoretical effort required to lift a load of 30N assuming no energy losses the efficiency if the actual effort is 10N

Answer 1

20/4 = 5 = ideal mechanical advantage
30 N / 5 = 6 Newtons would do it in ideal world
but we needed 10 N
efficiency=100 *Work out / work in = 600/10 = 60%

Answer 2

VR= 5
E= 6
Efficiency = 50%