Question

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 1. Efficiency of the machine 2. The effort applied

Answer 1

Step-by-step explanation:

Load will be moved by 4L when effort moves by distance L .

4L = 10 m ( given )

L = 2.5 m

work output = work input = 400 x 10 = 4000 J

work by friction = 100 J

net work output = 3900 J .

efficiency = net output of work / work input

= (3900 / 4000) x 100

= 97.5 %

2 )

work input = 4000 J

distance moved by effort = 2.5 m

If effort be F

F X 2.5 = 4000

F = 1600 N .