Physics
State four differences between a single fixed pulley and a single movable pulley.
Machines
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Answer
| Single fixed pulley | Single movable pulley |
|---|---|
| It is fixed to a rigid support. | It is not fixed to a rigid support. |
| Its ideal mechanical advantage is 1. | Its ideal mechanical advantage is 2 |
| Its velocity ratio is 1. | Its velocity ratio is 2. |
| The weight of pulley itself does not affect its mechanical advantage. | The weight of pulley itself reduces its mechanical advantage. |
| It is used to change the direction of effort from upwards to downwards. | It is used as a force multiplier. |
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Related Questions
Draw a labelled diagram of an arrangement of two pulleys, one fixed and other moveable. In the diagram, mark the directions of all forces acting on it. What is the ideal mechanical advantage of the system? How can it be achieved?
The diagram alongside shows an arrangement of three pulleys A, B and C. The load is marked as L and the effort as E.
(a) Name the pulleys A, B and C.
(b) Mark in the diagram the direction of load (L), effort (E) and tension T1 and T2 in the two strings.
(c) How are the magnitudes of L and E related to the tension T1?
(d) Calculate the mechanical advantage and velocity ratio of the arrangement.
(e) What assumptions have you made in parts (c) and (d)?
Draw a diagram of combination of three movable pulleys and one fixed pulley to lift up a load. In the diagram, show the directions of load, effort and tension in each strand. Find:
(i) the mechanical advantage,
(ii) velocity ratio and
(iii) the efficiency of the combination in the ideal situation.
The diagram alongside shows a pulley arrangement.
(a) Name the pulleys A and B.
(b) In the diagram, mark the direction of tension on each strand of string.
(c) What is the purpose of the pulley B?
(d) If the tension is T, deduce the relation between (i) T and E, and (ii) E and L.
(e) What is the velocity ratio of the arrangement?
(f) Assuming that the efficiency of the system is 100%, what is the mechanical advantage?