# Hanging bag by a vertical rope

#### Toranc3

1. Homework Statement

A 115kg mail bag hangs by a vertical rope 3.3m long. A postal worker then displaces the bag to a position 2.2m sideways from its original position, always keeping the rope taut.

As the bag is moved to this position, how much work is done by the rope?
2. Homework Equations

W=F*d

3. The Attempt at a Solution
Tx=-Tcos(theta)
Ty=Tsin(theta)

W=-Tcos(theta)*d

T/3.3m =mg/2.5m to get T

I wanted to know why this is zero. Doesn't the Tension have a negative component in the opposite direction of motion, so the work done will be negative. The answer is zero but I just wanted an explanation on this one. Thanks!
1. Homework Statement

2. Homework Equations

3. The Attempt at a Solution

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#### lewando

Homework Helper
Gold Member
Wrope = Fropedrope.

If Wrope = 0 and Frope (tension) is nonzero, what must be true about drope?

its zero

#### Toranc3

ive got it! thanks!!

#### lewando

Homework Helper
Gold Member
Which it is, due to the length of the rope not changing. All clear?

#### Toranc3

Which it is, due to the length of the rope not changing. All clear?
Wouldn't it also be correct to say that T is perpendicular to the displacement?

#### lewando

Homework Helper
Gold Member
No, it is at some angle, but not 90°.

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