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Figure shows a system of four pulleys. The upper two pulleys are fixed and the lower two are movable.
Figure shows a system of four pulleys. The upper two pulleys are fixed and the lower two are movable.
Class 10 | ICSE | Machines | Physics | Selina
Figure shows a system of four pulleys. The upper two pulleys are fixed and the lower two are movable.

(a) Draw a string around the pulleys. Also show the point of application and direction in which the effort E is applied.
(b) What is the velocity ratio of the system?
(c) How are load and effort of the pulley system related?
(d) What assumption do you make in arriving at your answer in part (c)?

Solution –

(a)

(b) Velocity ratio of the system is equal to the number of pulleys, n = 4

(c) Expression of the relation between load and effort is

M.A. = load / effort = n = 4

Therefore, Load = 4 × effort

(d)

(i) The effort is applied downwards because there is no friction in the pulley bearings,

(ii) the weight of the lower pulleys is insignificant, and

(iii) there is no friction in the pulley bearings.

i

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