Advertisements
Advertisements
Question
When does a force perform work?
Advertisements
Solution 1
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).
Solution 2
-
Displacement Occurs: The object on which the force is applied must move (displace) in response to the force.
-
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°.
APPEARS IN
RELATED QUESTIONS
In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east, as shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.
State two conditions when no work is done by a force.
Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.
When do we say that work is done? Write the formula for the work done by a body in moving up against gravity. Give the meaning of each symbol which occurs in it.
A boy tries to push a truck parked on the roadside. The truck does not move at all. Another boy pushes a bicycle. The bicycle moves through a certain distance. In which case was the work done more : on the trick or on the bicycle? Give a reason to support your answer.
What is the ratio of SI units to CGS units of 'work'?
Fill in the boxe to show the corresponding energy transformation.
A is a push or a pull ______.
A ______ should act on an object.
