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प्रश्न
When does a force perform work?
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उत्तर १
Work is said to be done only when the force applied on a body makes the body move (i.e. if there is some displacement or motion occurred due that force).
उत्तर २
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Displacement Occurs: The object on which the force is applied must move (displace) in response to the force.
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Component of Force Along Displacement: There must be a component of the applied force in the direction of the displacement.
Formula for Work:
Work = Force × Displacement × cos θ
θ is the angle between the force and displacement directions.
Key Points:
- If the displacement is zero, no work is done, even if a force is applied.
- If the force is perpendicular to the displacement (θ = 90°), no work is done because cos 90°.
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संबंधित प्रश्न
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A sailboat is moving due to wind energy.
A force acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of the force. What should be the value of θ to get the maximum positive work?
A force of 30 N acts on a body and moves it through a distance of 5 m in the direction of force. Calculate the work done by the force.
A car is being driven by a force of 2.5 ✕ 1010 N. Travelling at a constant speed of 5 m/s, it takes 2 minutes to reach a certain place. Calculate the work done.
An object is dropped from a height H. when is its
(i) P.E. maximum,
(ii) K.E. maximum,
(iii) P.E. = K.E.?
Give an example
Electrical energy changes to heat energy.
A force is applied on a body of mass 20 kg moving with a velocity of 40 ms−1. The body attains a velocity of 50 ms−1 in 2 seconds. Calculate the work done by the body.
