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प्रश्न
What is a lever? How are the orders of the lever determined?
उत्तर
A lever is a simple machine consisting of a rigid rod that is capable of turning around a pivot called a fulcrum. It has three parts, namely effort, load, and fulcrum.
- Fulcrum: The rod of the lever rests on it and the lever rotates about it.
- Load: The weight lifted by the liver is called the load.
- Effort: The force applied on the other end of the rod to lift the load is called the effort.
The orders of the lever are determined depending on the position of the effort, the fulcrum, and the load.
- Lever of the first order: When the fulcrum is situated between load and effort, we call it a lever of the first order. For example, beam balance, a crowbar, a see-saw."
- Lever of second order: When the fulcrum and effort are situated at the two opposite ends of the lever and a load is placed in between them, we call it a lever of second order. For example, a nutcracker, a wheel-barrow, etc.
- Lever of the third order: When the fulcrum and load are situated at the opposite ends of the lever and an effort is applied somewhere between them, we call it a lever of the third order. For example, a pair of tongs, a fishing rod, etc.
संबंधित प्रश्न
Fill in the blank:
The useful work done by an actual machine is always ............ than the work done on the machine.
What is the principle on which a machine works?
Write an expression for the mechanical advantage of an inclined plane in terms of its length I and vertical height h.
Define Efficiency
Fig. shows a spade. It is being used to lift soil weighing 30N from the ground.
(a) Mark the direction of the least force on the handle necessary to keep the spade balanced.
(b) Calculate the least force on the handle necessary to keep the spade balanced (the weight of the spade is negligible).
(c) If the left hand was move towards the soil on the spade, would the force on the handle necessary to keep the soil balance the greater or less? Give a reason for your answer.
(d) To which class of lever does the spade belong?
Write an expression for the mechanical advantage of an inclined plane.
Give an example of the following use of a machine to obtain gain in force.
Classify the following as a lever, a pulley and an inclined plane:
An axe
Which machine will you use to do the following work? Write their type.
To cut vegetables.
Why is this so machines have to be maintained?
