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Question
Draw a diagram showing a block and tackle system of 4 pulleys.
(i) State, how many strands of tackle support the load?
(ii) Draw arrows to represent tension in each strand.
(iii) Find the mechanical advantage of the system, stating the assumptions made.
(iv) If the load is pulled up by a distance 1m, how much does the effort end move?
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Solution
The adjacent diagram shows a block and tackle system of 4 pulleys.
(i) Four strands of tackle support the load.
(ii) The tension in each strand is shown by the arrow marked as T.
(iii) If we neglect the friction of the pulleys and weight of the pulleys in the lower block, then:
L = 4T
and E = T
∴ M.A. =`"L"/"E"`
= `(4"T")/"T"`
= 4.
(iv) If the load is pulled up by a distance 1m, the effort end moves by 4 m.
RELATED QUESTIONS
In which direction does the force need to applied, when a single pulley is used with a mechanical advantage greater than one? How can you change the direction of force applied without altering its mechanical advantage? Draw a labelled diagram of the system.
Give reason for the following:
In a single fixed pulley, the velocity ratio is always more than the mechanical advantage.
Give reason for the following:
The lower block of a block and tackle pulley system must be of negligible weight
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In a single fixed pulley, the velocity ratio is always more than the mechanical advantage.
Name a machine which is used to:
change the direction of force applied.
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What is a block and tackle system of pulleys?
A type of single pulley is very often used as a machine even though it does not give any gain in mechanical advantage. For what purpose is such a pulley used?
The pulley system shown in the figure is to be used to lift a load W. If the man applying the effort cannot apply a force exceeding 1000 N, what is the maximum load that can be lifted?
The actual load that the man is finally able to lift turns out to be 2700 N. What are the values of the actual M.A., obtained, and the efficiency of the actual set-up?
A pulley is a machine made up of a ______.
