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प्रश्न
State two functions of a machine.
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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: In 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
Select the correct alternative:
A pulley is used because of it
What is the justification for using the pulley then ?
Answer the following in detail.
How does a pulley make work simpler?
Explain the working of a gear system.
Explain how a gear system can be used to obtain gain in torque? Given one example.
Give reason for the following:
The lower block of a block and tackle pulley system must be of negligible weight
Name a machine which is used to:
change the direction of force applied.
(a) Fig represents an incomplete diagram of a simple string pulley system. Copy this diagram on a new page and complete it and mark where the effort must be applied to lift the load.
(b) What is the velocity ratio of this system?
(c) If the pulley system is 80% efficient and the load is 720 N, then
(i) What effort must be applied to lift the load?
(ii) What work must be done must be done in lifting the load through a distance of 2 m using this machine?
In a single movable pulley system, a load of 125 kgf is lifted by an effort of 75 kgf. Find the percentage efficiency of system.
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)
