Can someone explain to me the signs on this vector problem

  • Thread starter Thread starter pyroknife
  • Start date Start date
  • Tags Tags
    Explain Vector
Click For Summary

Homework Help Overview

The discussion revolves around a vector problem involving the tension in a cable connecting two points in a three-dimensional space. The original poster is attempting to determine the correct vector representation for the force at point B based on the locations of points A and B.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster questions whether to calculate the position vector as B-A or A-B to find the corresponding force vector. They express confusion regarding the signs in their calculations and seek clarification on the correct approach.

Discussion Status

Participants are exploring the implications of vector directionality in relation to tension. Some have provided insights into the nature of tension as a pulling force, suggesting that the force vector should point away from point B. There is an ongoing dialogue about the relationship between the position vector and the force vector.

Contextual Notes

The original poster's inquiry is framed within the constraints of a homework assignment, which may impose specific expectations on how to approach vector calculations. There are also references to textbook examples that influence the discussion on sign conventions.

pyroknife
Messages
611
Reaction score
4

Homework Statement


For drawing purposes, I'm just going to state the locations of the 2 points. Cable AB carries a tension of 12 kN. Point A=(0,0,70) m and point B=(35,-25,10) m.
Find the corresponding force on point B as a vector.




okay now this part has me confused. I'm trying to find my r vector so I can get the unit vector out of that and multiply by the tension to get the corresponding force vector.

My question is do you do B-A or A-b to get the r vector? The only way I can match the signs in the book is to do A-B, but why would it be A-B instead of B-A?
 
Physics news on Phys.org
can someone also answer the question why the E field in the conductor w/ the 2 radius is 0? Shouldn't there be an e field due to the smaller conductor?
 
The direction of the force on B has to point away from B. Tensions pull, they don't push. A-B points away from B. B-A doesn't.
 
oh thank you for explaining. r vector and force vector always point in same direction correct?
 
pyroknife said:
oh thank you for explaining. r vector and force vector always point in same direction correct?

I like my explanation better. Tension pulls. It should point AWAY from B.
 

Similar threads

Vectors Directions: Where is this Resultant Vector Pointing?
  • · Replies 14 ·
Replies
14
Views
2K
Combined tensions of an RLC series circuit with AC current
  • · Replies 3 ·
Replies
3
Views
1K
Does distance affect torque in hanging sign problem?
  • · Replies 42 ·
2
Replies
42
Views
4K
Can A Vector Have Components Of Say Y or Z in the X-Hat Direction?
  • · Replies 8 ·
Replies
8
Views
1K
Syntax Error? x and y components of E field in unit vector form
  • · Replies 13 ·
Replies
13
Views
2K
Problem involving space elevators
  • · Replies 19 ·
Replies
19
Views
2K
Force acting on one side of a fluid
  • · Replies 22 ·
Replies
22
Views
1K
Displacement problem with unit vectors
  • · Replies 4 ·
Replies
4
Views
2K
Projectile Motion Using Vectors
  • · Replies 39 ·
2
Replies
39
Views
5K
The components of force and velocity vectors in circular motion
  • · Replies 11 ·
Replies
11
Views
3K