Question

7. A pulley system has 5 pulleys in all and is 90%
efficient. Calculate the:
(a) mechanical advantage,

(b) effort required to lift a load of 1000 N and

(c) resistance due to movable parts of the
machine and friction.​

Answer 1

Explanation:

Number of pulleyes in system n = 5

V. R. =5

n=90%=90/100

a) M. A. =n

M. A/5=90/100

M. A=90/100×5=4.5

b) load =1000N

load/effort=M.A

1000/E=4.5

effort =222.2N

c) let x be resistance due to movable parts of machine and friction

M. A=V.R=x/E

9/2=5-x/E

x=E(5-9/2)

=(1000×10)/45×1/2

=1000/9=111.1N