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Question
The diagram below shows a pulley arrangement.
- Name the pulleys A and B.
- In the diagram, mark the direction of tension on each strand of string.
- What is the purpose of the pulley B?
- If the tension is T, deduce the relation between
- T and E, and
- E and L.
- What is the velocity ratio of the arrangement?
- Assuming that the efficiency of the system is 100%, what is the mechanical advantage?
Solution
- Pulley A is a movable pulley.
Pulley B is a fixed pulley. - Tension T is marked in (f)
-
Pulley B's function is to reverse the direction of effort applied, moving it from upward to downward.
- Relation between:
- T and E are E = T.
- Between E and L, is E = `L/2`
- V.R. = `("Distance moved by effort" d_E)/("Distance moved by load" d_L)`
V.R. = `(2d)/d = 2` - M.A. = Efficiency × V.R.
= `100/100 xx 2 = 2`
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