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प्रश्न
Differentiate between a single fixed pulley and a single movable pulley.
State four differences between a single fixed pulley and a single movable pulley.
उत्तर
| Single fixed pulley | Single movable pulley | |
| 1. | This pulley has a fixed axis of rotation. | The axis of rotation of this pulley is not fixed. |
| 2. | The load is attached to one end of the rope. | The load is attached to the pulley. |
| 3. | Only the direction of the force is changed, not the magnitude. [We can lift the object higher, but the heaviness of load remains the same.] | The direction of the force as well as the magnitude of the force change. |
| 4. | The mechanical advantage of this pulley is 1. | The mechanical advantage of this pulley is 2. |
| 5. | Example: Used to draw water from wells. | Example: Used in construction cranes, Weight lifting, machines in the gym, etc. |
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संबंधित प्रश्न
A block and tackle system has V.R. = 5.
Draw a neat labeled diagram of a system indicating the direction of its load and effort
Fill in the blank:
A pulley is used to change ........................
What is the mechanical advantage of an ideal pulley?
Solve the following numerical problem.
What effort will be required to lift a load of 500 N by a single movable pulley? [Hint: Mechanical advantage of a single movable pulley is two].
What should be the gear ration of a car : equal to 1, less than 1 or greater than 1, while gaining speed on the road ?
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?
Draw a diagram of a 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:
- mechanical advantage,
- Velocity ratio and
- efficiency of the combination in ideal situation.
A block and tackle pulley system has a velocity ratio 5. Draw a labelled diagram of this system. In your diagram, indicate clearly the points of application and the directions of the load and effort.
Give reason for the following:
In case of a block and tackle arrangement, the mechanical advantage increases with the increase in the number of pulleys.
The diagram below shows a pulley arrangement :
(i) Copy the diagram and mark the direction of tension on each strand of the string.
(ii) What is the velocity ratio of the arrangement ?
(iii) If the tension acting on the string is T, then what is the relationship between T and effort E ?
(iv) If the free end of the string moves through distance x, find the distance by which the load is raised.
Give a reason for the following:
In a single fixed pulley, the velocity ratio is always more than the mechanical advantage.
What is a block and tackle system of pulleys?
State two reasons, why the efficiency of a pulley system is not 100 percent?
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.
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?
Diagram given below shows an arrangement of four pulleys. A load L is attached to the movable lower block and effort E is applied at the free end of the string.
Copy the diagram; and
(i) Draw arrows to indicate tension in each part of the string; and
(ii) Calculate the mechanical advantage of the system.
| 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?
