Scales stacked together: reading on each?

[tambourine]

Homework Statement

A standard scale (shown below) has an internal spring and a dial which shows the force exerted on the pan by this spring. The instrument has a mass of about 1 kg and weight 10 N. Ignore the weight of the light pan. To conserve space, the new metric commissioner stacks a pair of those scales as shown, one upside down on the other. We see them from the back, but what should the dials be showing (in Newtons)? Explain.

The Attempt at a Solution

from what i understand, they should both show 10 N. the weight of the top scale causes the bottom one to read 10 N, and the normal force pushes back up on the top scale with 10 N. is this correct?

 

[Doc Al]

Sounds good to me.

 

[baba89]

I would agree with your understanding. The weight of the top scale would cause the bottom scale to read 10 N, while the normal force from the bottom scale would push back up on the top scale with 10 N. This is because the weight of the top scale is transferred to the bottom scale through the normal force, resulting in a total force of 10 N on each scale. This is an example of Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction.

 

[Moetasim]

Yes, your understanding is correct. Since the two scales are stacked together, the weight of the top scale (10 N) will be transferred to the bottom scale, causing it to read 10 N as well. This is due to the fact that the normal force exerted by the bottom scale on the top scale will also be 10 N, balancing out the weight. Therefore, both dials should show a reading of 10 N.