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प्रश्न
Answer the following in short.
Explain the various functions that a machine can perform.
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उत्तर
Various functions that a machine can perform are :
- Changing the direction of applied force − Example: When a flag is hoisted with the help of a pulley.
- Changing the magnitude of applied force − Example: Bottle opener multiplies the applied force and much less effort is required to open the cap.
- Applying force at a convenient point − Example: hi a pair of scissors, the input force is applied at the handle of the scissors which cuts the paper at the other end of the blade.
- Changing the speed of an object − Example: While riding a bicycle, force is applied on pedals which multiplies the speed.
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संबंधित प्रश्न
Rohan exerts a pull of 150 kgf. What is the maximum load he can raise with this pulley system if its efficiency = 75%?
State two functions of a machine.
What is a single movable pulley? What is its mechanical advantage in the ideal case?
Give two reasons why the efficiency of a single movable pulley system is not 100%.
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.
What is a block and tackle system of pulleys? What precautions would you observe while rounding the string so that the effort is applied in the downward direction?
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.
A man raises a load of 360 kgf using a block and tackle system of 3 pulleys. If the efficiency of the pulley system is 60%, what effort is applied by the man?
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)
