Question

A block and tackle system of pulleys has velocity ratio 4.

1. Draw a neat labelled diagram of the system indicating clearly the points of application and direction of load and effort.
2. What will be its V.R., if the weight of the movable block is doubled?

Answer 1

(a) A block-and-tackle system with V.R. = 4 has two pulleys in the upper fixed block and two pulleys in the lower movable block. The load is attached to the lower block, and the effort is applied at the free end of the string.

(b) The velocity ratio depends only on the arrangement and the number of supporting strands. It does not depend on the weight of the pulleys.

Therefore, even if the weight of the movable block is doubled, the V.R. remains the same.

V. R. = 4