A force is applied to a cart to displace it up the incline at constant speed. Scenario A: A force acts rightward upon an object as it is displaced rightward. Because the inner surface of the balloon is flexible, that surface moves outward. In such an instance, the force vector and the displacement vector are in the opposite direction.
So, a frustrated person pushing against a wall, only to exhaust himself, is not doing any work because the wall does not move.
Driving to your job is not work because you just sit, but the energy your car engine uses to move the car does work. We need to simplify things a little bit more. This agrees with our everyday notion of work. Thus constraint forces do not perform work on the system, because the component of velocity along the constraint force at each point of application is zero.
Certain things we think of as hard work, such as writing an exam or carrying a heavy load on level ground, are not work as defined by a scientist.
Extra credit if you can tell the difference between the two. Nothing is being done — not even work. The Meaning of Negative Work On occasion, a force acts upon a moving object to hinder a displacement.
Negative work is also done on a textbook when it is lowered vertically at a constant velocity.