a 6 kg box is stacked on top of a 15 kg box. anet leans down and pulls her elbow on the top box, exterting a force downward of -122N. what is the normal force on the top box
I am confused about whether Annette (or anet) pulls her elbow on the top box, or puts it there.
Since the top box is not going to move, the normal force on it (at the bottom, upward) equals the sum of the downward forces on it: 122N and (6kg)*g. That would be 180.8 N
To find the normal force on the top box, we need to understand and apply Newton's third law of motion, which states that for every action, there is an equal and opposite reaction.
In this case, Anet exerts a force downward on the top box, which we'll consider as the action. According to Newton's third law, the top box will exert an equal and opposite force upward on Anet, which we'll consider as the reaction.
Since the boxes are stacked on top of each other, they are in contact, and the contact force between them is the normal force. So, the normal force on the top box is equal in magnitude and opposite in direction to the reaction force exerted on Anet.
Given that Anet exerts a downward force of -122 N on the top box, the reaction force exerted on Anet is +122 N (considering the direction).
Therefore, the normal force on the top box is 122 Newtons.