A block and tackle having a velocity ratio of 5 is used to raise a load of 400N through a distance of 10m. If the work done against friction is 100J. Calculate

Question

1. Efficiency of the machine
2. The effort applied

Answer 1

1. W = F*d = 400*10 = 4,000 J.
e = 4000/(4000+100) = 0.98 = 98 %.

2. e = L/E*Vr
0.98 = 400/5E
E = 82 N.

Answer 2

Can you please explain the answer 2.well for me .

Answer 3

Thank you

Answer 4

I don't understand