- #1

iJamJL

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## Homework Statement

ASSUME: For all parts of this question, friction is negligible.

A vertical rope is used to lower a block of mass M = 40.9 kg at a constant acceleration of magnitude a = 3.09 m/s2. Find WT, the work done by the tension in the cord if the mass moves down distance s = 8.01 m.

## Homework Equations

W=F*s

F=mg

F=ma

## The Attempt at a Solution

My problem really roots from my inability to draw and set up the problem correctly because I never truly understood how to do that with tension.

Nevertheless, I do know that since the box is going down, and gravity goes in that direction as well, we could make tension positive. Since tension is positive, does that mean we set it up so that T-mg=ma?

The next part would be the box being lowered at a=3.09m/s/s. Since it's being lowered, which is the same direction as mg, does that mean that T is still positive? So we would have:

T-m(a1)=m(a2)

T-mg = m(a2)

From above. Obviously, something is wrong here. Which T should be negative? Also, I don't really understand which accelerations to use for the result. In T-m(a1), a1 is the acceleration that is given. I wasn't sure what to put after that, so I just put a2. Should it be 0? I'm just confused overall about setting this up.