Statics - Finding Tension

Homework Equations

The answer in the back on the book shows 4.06i -7.61j + 5.07k. I do not understand why my signs are backwards.

The Attempt at a Solution

I ended with -4.06i +7.61j - 5.07k

Answers and Replies

gneill
Mentor
The tension involved is a vector that points from B towards A. You've created a vector rab that points from A to B.

ok thank you. Since i did not see an arrow i was not sure which direction to pick. How did you tell?

gneill
Mentor
ok thank you. Since i did not see an arrow i was not sure which direction to pick. How did you tell?
It's difficult to push with a cable :)

The tension involved is a vector that points from B towards A. You've created a vector rab that points from A to B.

It's difficult to push with a cable :)

That is a good point. Thank you

That is a good point. Thank you

Additionally, there is a weight pulling the boom downwards (or in the negative z-direction). In order to counteract this, the cable needs to pull it upwards (positive z-direction).