Which of the following is not an example of work?
A.
raising a barbell over your head
B.
picking up a box off the floor
C.
holding a tray in the cafeteria line
D.
pushing a box across the floor
I think its C.
Force times distance in direction of force
If not moving in cafeteria line - no work
If moving forward in line and weight of tray is down, force not in direction of motion --> NO WORK
So yes, C
Ty :)
To determine which of the given options is not an example of work, we need to understand the concept 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 is calculated as the product of force and displacement, W = F * d, where W represents work, F represents the applied force, and d represents the displacement.
Let's analyze each option:
A. Raising a barbell over your head: This involves applying a force to the barbell, lifting it against the force of gravity, and displacing it vertically. Therefore, this is an example of work.
B. Picking up a box off the floor: This action also involves applying a force to the box, lifting it against the force of gravity, and displacing it vertically. Hence, this is an example of work.
C. Holding a tray in the cafeteria line: This option involves exerting a force to counteract the force of gravity to maintain the tray at a fixed height. However, no displacement occurs since the tray remains stationary. Therefore, this is NOT an example of work.
D. Pushing a box across the floor: By pushing the box, you apply a force to it, causing it to move horizontally. Consequently, work is done in this case as there is both a force and displacement involved.
Based on this analysis, you are correct. Holding a tray in the cafeteria line (option C) is not an example of work, while the other options are examples of work.