- #1

awelex

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here's a problem I did earlier today. I think I got it right, but I'd appreciate it if somebody could check. Also, is there a different way to solve this problem?

## Homework Statement

Two masses Ma and Mb are connected through a heavy rope with mass Mr. The top mass Ma is hanging from a from a massless rope that is that is attached to a helicopter that moves upwards with acceleration a. Find the tension in the top rope as well as the tensions in the bottom (heavy) rope.

I labeled the tension of the top rope T1, the tension of the heavy rope pulling downward on Ma T2.1, and the tension pulling upward on Mb T2.2.

## Homework Equations

For mass A: Fnet = Ma * a

--> T1 - T2.1 - Ma * g = Ma * a

--> T1 - T2.1 = Ma * a + Ma * g

For mass B: Fnet = Mb * a

--> T2.2 - Mb * g = Mb * a

--> T2.2 = Mb * a + Mb * g

This already gives us the tension from the heavy rope pulling upwards on the second mass.

For the entire system, without the top rope:

Fnet = (Ma + Mb + Mr) * a

--> T1 - (Ma + Mb + Mr) * g = (Ma + Mb + Mr) * a

--> T1 = (Ma + Mb + Mr) * (a + g)

I plugged this into the earlier equation with T1 and T2.1:

(Ma + Mb + Mr) * (a + g) - T2.1 = Ma * (a + g)

--> T2.1 = (Mb + Mr) * (a + g)

So we have:

T1 = (Ma + Mb + mr) * (a + g)

T2.1 = (Mb + Mr) * (a + g)

T2.2 = Mb * (a + g)

## The Attempt at a Solution

See above.

Is this correct?