In which situation is no work being done?

a person carrying a box from one place to another
a person picking up a box from the ground
a person pushing a box from one place to another
a person pulling a box from one place to another

probably the first.

To determine in which situation no work is being done, we need to understand the definition of work in physics. Work is defined as the transfer of energy that occurs when a force is applied to an object and the object is displaced in the direction of the force. Mathematically, work (W) is calculated as the product of the force applied (F) and the displacement (d) in the direction of the force: W = F * d * cos(theta), where theta is the angle between the force and the displacement vectors.

Now, let's analyze each situation to determine if work is being done:

1. A person carrying a box from one place to another: In this case, work is indeed being done. The person exerts a force on the box, and the box is displaced as the person walks. As the displacement of the box is in the same direction as the force applied, work is being done.

2. A person picking up a box from the ground: When a person picks up a box from the ground while holding it at a constant height, no work is being done. This is because no displacement occurs in the direction of the force applied. The only force applied is to counteract the force of gravity, which does not result in any displacement.

3. A person pushing a box from one place to another: In this situation, work is being done. The person exerts a force on the box and causes it to move in the direction of the force applied. As long as there is displacement in the direction of the force, work is done.

4. A person pulling a box from one place to another: Similar to pushing, if a person pulls the box and the box moves in the direction of the applied force, then work is being done. The displacement is in the same direction as the force, allowing work to occur.

Therefore, the situation in which no work is being done is when a person picks up a box from the ground, as there is no displacement in the direction of the force applied.