HOw do u know if a force acting on an object does no work?

Is it because the force is not in the direction of the objects motion, the force is greater than the force of friction, or the object accelerates?


* please explain how u know this %26amp; the first person with the right answers gets 5 stars *HOw do u know if a force acting on an object does no work?
If the force acting on the object doesnt result in displacement of the particles in relation to the surroundings of the system under consideration, then the work done is zero.





Mathematically the work done is zero when the displacement is at right angle (90 degrees) to the direction of the force.


Since work is calculated as force x displacement x cos(theta)


i.e. W = F x d x cos (theta)


where theta is the angle between the force and the displacement.





Eg : The earth does no work on the moon since the motion of the moon is at right angle (tangential) to the direction of the force applied by the earth.HOw do u know if a force acting on an object does no work?
work is force times distance. so if there is either no force or no distance, then the object does no work.
Whenever there is a Force acting on any object, even though there is no displacement it does some work, to find out that u have to calculate the co-efficient of surface and frictional force.





But it always does some work.
If a force acting on an object does not move or deform the object, then it does no work. The previous answer is incorrect.
hick_ninja is right