Action/reaction on superposed masses

[Werg22]

If two masses are superposed one on the other and my hand is holding supporting them, the force that is applied on the system is equivalent to their weight. So the reaction of those two masses toward my hand is also equivalent to their combined weight. If mass 1 is on my hand, and mass 2 on mass 1, mass 1 transfers an amount of force to mass 2, which is equivalent to its weight. By action reaction this weight also applies on mass 1. Why is it that the reaction of mass 2 is directly transferred to my hand trought mass 1 and not acting directly on it?

 

[Fermat]

.. Why is it that the reaction of mass 2 is directly transferred to my hand trought mass 1 and not acting directly on it?

It's not. The reaction is indirect.
Mass2 is directly suppported by mass1, which is directly supported by your hand.
Your hand must supply the reaction that supports both masses, otherwise they will fall to the ground. This reaction acts directly on mass1 since that is the object that your hand is in contact with.
Mass1 must then supply (directly) a reaction upon mass2, where it is in contact with it, and so prevent mass2 from falling through mass1 !

 

[quicknote]

I would like to clarify that the concept of action and reaction is a fundamental principle in physics, known as Newton's Third Law of Motion. This law states that for every action, there is an equal and opposite reaction.

In this scenario, the action is the force applied by your hand on the two masses, and the reaction is the force applied by the two masses on your hand. This is because every time you hold an object, your hand exerts a force on it, and the object exerts an equal and opposite force on your hand.

The reason why the reaction of mass 2 is transferred to your hand through mass 1 is due to the principle of superposition. When two masses are stacked on top of each other, their weights are added, and the combined weight is transferred to the bottom mass. In this case, mass 2 is resting on mass 1, so the weight of mass 2 is transferred to mass 1, and then to your hand.

It is important to note that the force applied by mass 2 on mass 1 is not the same as the force applied by mass 1 on mass 2. This is because the force applied by mass 1 on mass 2 is in the opposite direction of the force applied by mass 2 on mass 1. However, the magnitude of these two forces is equal, as per Newton's Third Law.

In conclusion, the reaction of mass 2 is transferred to your hand through mass 1 due to the principle of superposition and Newton's Third Law of Motion. This is a fundamental concept in physics that helps us understand the forces acting on a system and their effects.