Advertisements
Advertisements
Question
When does a force perform work?
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
The S.I. unit of energy is .............
Write the expression for work done by a force.
A vessel containing 50 kg of water is placed at a height 15 m above the ground. Assuming the gravitational potential energy at ground to be zero, what will be the gravitational potential energy of water in the vessel? (g = 10 m s-2)
Give one example each in which a force does (a) positive work (b) negative work, and (c) zero work.
A person of mass 50 kg climbs a tower of height 72 metres. Calculate the work done. (g = 9.8 m s−2).
On what factors does the work done by a force depend?
A block of mass 20 kg is pulled up a slope (fig.12) with a constant speed by applying a force of 500 N parallel to the slope. A and B are initial and final positions of the block.
(a) Calculate the work done by the force in moving the block from A and B.
(b) Calculate the potential energy gained by the block.
Give an example
Chemical energy changes to electrical energy.
State larger units of power.
A force can cause an object to change its ______.
What is work?
