Work is being done in which of these situations? All motions are at a constant velocity (including velocity = zero).

A.

Jessica pushes a 25 kilogram cart a distance of 10 meters.

B.

Bane carries a 20 kilogram box a distance of 50 meters.

C.

A weightlifter holds a 100 kilogram barbell over his head.

D.

Ali is trying to push a truck away from the parking lot.

E.

Yana carries a 5 kilogram bag a distance of 1 kilometer.

A. Jessica pushes a 25 kilogram cart a distance of 10 meters.

Explanation:

Work is said to be the product of the force applied to a body and the appreciable distance the body covers. Work is done upon an object if the forces acting on the object causes a displacement. In other words work determines the energy transfer due to external force causing a body to move a distance.

For work to be done their must be a force causing an appreciable displacement. Mathematically work can be represented as

Work = Force * distance

From the option above, the option B, their is no force to make the body move. Bane only carried the box but it (box) didn't move. Option C, the weight lifter only held the barbell over the head. There was no indication he lifted it over his head. Option D, Ali was only trying to apply a force to the body but their was no displacement of the body. Option E, Yana carried the bag and was moving with it. The body which is the bag was not moved by a force.

The correct option is A because an external force (Jessica pushed) was applied on a body (cart) and the body covered a distance.

Work is being done in the situation A, B, E

Explanation:

The work is always done when the load is moved some distance in case A, B, and E the load was moved 10, 50 meters and 1 km respectively.

In cases C and D there was no movement.