(a) Name the unit of work done used on the subatomic scale.
(b) To which class of lever does a pair of scissors belong?
(c) A stone is tied to a string and displaced from A to B by application of constant force F in three different ways as shown below.
Arrange the three cases in ascending order of the work done by the force. (Given AJB is a semicircle, θ < 90° and AB = 20 m)
(a) electron volt (eV)
(b) Class I lever
(c) Work done is W = Force × Displacement × cos θ.
In Case 1, force is perpendicular to displacement, so work done is zero.
In Case 2, force acts along displacement, so work done is maximum.
In Case 3, θ < 90°, so the work done is greater than Case 1 but less than Case 2.
Therefore, the ascending order is: Case 1 < Case 3 < Case 2.
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