How Does Newton's Third Law Apply to Stacked Blocks in an Elevator?

[jessemarquez]

Homework Statement

Three blocks are stacked on top of each other inside an elevator as shown in the figure.
Answer the following questions with reference to the eight forces defined as follows.

the force of the 3kg block on the 2kg block, F of 3 on 2,
the force of the 2kg block on the 3kg block, F of 2 on 3,
the force of the 3kg block on the 1kg block, F of 3 on 1,
the force of the 1kg block on the 3kg block, F of 1 on 3,
the force of the 2kg block on the 1kg block, F of 2 on 1,
the force of the 1kg block on the 2kg block, F of 1 on 2,
the force of the 1kg block on the floor, F of 1 on floor, and
the force of the floor on the 1kg block, F of floor on 1.

Assume the elevator is at rest. Rank the magnitude of the forces.
Rank from largest to smallest.

__________
| |
| |
| 3 kg |
|________|
| |
| 2 Kg |
|______ |
| |
| 1 kg |
|______|______

The Attempt at a Solution

F of floor on 1 and F 1 on floor, F of 3 on 2 and F of 2 on 3, F of 2 on 1 and F of 1 on 2, F of 3 on 1 and F of 1 on 3.

 

[jessemarquez]

can anyone offer any insight if the order stated is correct.

 

[m2003]

I understand that Newton's Third Law states that for every action, there is an equal and opposite reaction. In this scenario, the action would be the force exerted by one block on another, and the reaction would be the force exerted by the other block on the first one. Therefore, the magnitude of the forces between the blocks will be equal and opposite.

Based on this understanding, the ranking of the forces from largest to smallest would be:
1. F of floor on 1 and F of 1 on floor - these forces are equal in magnitude and act in opposite directions, so they cancel each other out and have no net effect on the blocks.
2. F of 3 on 2 and F of 2 on 3 - these forces are also equal in magnitude and act in opposite directions, so they cancel each other out and have no net effect on the blocks.
3. F of 2 on 1 and F of 1 on 2 - these forces are equal in magnitude and act in opposite directions, so they cancel each other out and have no net effect on the blocks.
4. F of 3 on 1 and F of 1 on 3 - these forces are equal in magnitude and act in opposite directions, so they cancel each other out and have no net effect on the blocks.

Therefore, the ranking of the forces from largest to smallest would be: F of floor on 1 and F of 1 on floor, F of 3 on 2 and F of 2 on 3, F of 2 on 1 and F of 1 on 2, F of 3 on 1 and F of 1 on 3.