Question

The diagram below shows a pulley arrangement.

1. Name the pulleys A and B.
2. In the diagram, mark the direction of tension on each strand of string.
3. What is the purpose of the pulley B?
4. If the tension is T, deduce the relation between
   1. T and E, and
   2. E and L.
5. What is the velocity ratio of the arrangement?
6. Assuming that the efficiency of the system is 100%, what is the mechanical advantage?

Answer 1

1. Pulley A is a movable pulley.
   Pulley B is a fixed pulley.
2. Tension T is marked in (f)

3. Pulley B's function is to reverse the direction of effort applied, moving it from upward to downward.

4. Relation between:
   1. T and E are E = T.
   2. Between E and L, is E = `L/2`
5. V.R. = `("Distance moved by effort"  d_E)/("Distance moved by load"  d_L)`
   V.R. = `(2d)/d = 2`
6. M.A. = Efficiency × V.R.
   = `100/100 xx 2 = 2`