How Much Work is Done by the Rope in Displacing a 115kg Hanging Mail Bag?

[Toranc3]

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?

Homework Equations

W=F*d

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!

 

[lewando]

W_rope = F_roped_rope.

If W_rope = 0 and F_rope (tension) is nonzero, what must be true about d_rope?

 

[Toranc3]

its zero

 

[Toranc3]

ive got it! thanks!

 

[lewando]

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]

No, it is at some angle, but not 90°.