What are the readings on the two connected spring scales?

[erinnn]

I'm in Physics 11 right now, and today we were given a question that if we can figure out, we will receive bonus marks on our next test.

I'm not asking you to solve it for me, (that'd be nice, ahaha), but I just don't know where to start.

We did a lab where the front of these spring scales were covered. There were two scales, connected one above the other. The hook on the bottom of the lower scale was tied down with a string with 10N of tension. The top scale held the first scale, and also a 5N weight.

We are supposed to try and figure out what each scale read. I don't know where to begin AT ALL. We were told to think of the laws of tension, inertia, of Hooke's Law and that was it.

I've been trying to figure it out ever since 2nd block..like 8 hours ago. Ahahah... HELP!

 

[HallsofIvy]

The lower scale doesn't "know" about the upper scale. As far as the lower scale is concerned, it is attached to a wall or shelf just like it would be if you were just using it to weigh something. That should tell you what the lower scale reads. As for the upper scale what forces are pulling down on it? (Do you know the weight of the lower scale or are you just assuming it is very small compared to the other forces?)

 

[erinnn]

thank you.

the lower scale was set to 0, so it's "weightless."