Advertisements
Advertisements
Question
A pulley system has three pulleys. A load of 120 N is overcome by applying an effort of 50 N. Calculate the Mechanical Advantage and Efficiency of this system.
Advertisements
Solution
Given: Load = 120 N
E = 50 N
Number of pulleys (n) = 3
For this pulley system,
V.R. = 3
1) Mechanical advantage of pulley system is
M.A. = `L/E`
= `120/50`
= 2.4
2) The efficiency of the system is
`eta = (M.A.)/(V.R.)`
= `(2.4)/n`
= `2.4/3`
= 0.8
= 80 %
RELATED QUESTIONS
Select the correct alternative:
A pulley is used because of it
In a gear system, the gear ration of the driving wheel A and driven wheel B is 10:1. To rotate the driven wheel B in the direction of driving wheel A, the driving wheel A is engaged with other wheel C. what should be the gear ratio of the wheels A and C?
What is a single movable pulley? What is its mechanical advantage in the ideal case?
The mechanical advantage of an ideal single movable pulley is ______.
Give a reason for the following:
In a single fixed pulley, the velocity ratio is always more than the mechanical advantage.
Give reason for the following:
In case of a block and tackle system, the mechanical advantage increases with the increase in the number 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. Name the type of pulley used.
Draw a diagram of a single fixed pulley and obtain expressions for its:
(i) Mechanical advantage,
(ii) Velocity ratio, and
(iii) Efficiency, in the ideal case.
| Meera chose to use a block and tackle system of '9' pulleys instead of a single movable pulley to lift a heavy load. |
Why should she connect more number of pulleys in the upper fixed block?
A block and tackle system of pulleys has a velocity ratio of 4.
- Draw a labelled diagram of the system indicating clearly the direction of the load and effort.
- Calculate the potential energy of the load 100 kgf lifted by this pulley to a height 5 m. (g = 10 ms−2)
