What is the Direction of A X B Using the Right Hand Rule?

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SUMMARY

The discussion focuses on determining the direction of the cross product A X B using the right-hand rule in various scenarios. In cases where vector A points east and vector B points south, the resultant vector points into the page. When A points east and B points straight down, the resultant also points into the page. For A pointing straight up and B pointing north, the result remains the same, as does the case where A points straight up and B points straight down. The right-hand rule is clarified as using the right hand to orient fingers along the vectors, with the thumb indicating the direction of the resultant vector.

PREREQUISITES
  • Understanding of vector notation and direction
  • Familiarity with the right-hand rule for vector cross products
  • Basic knowledge of three-dimensional coordinate systems
  • Concept of orthogonal axes (east-west, north-south, up-down)
NEXT STEPS
  • Study the right-hand rule for vector cross products in detail
  • Learn about vector operations in multivariable calculus
  • Explore visual aids for understanding vector directions and cross products
  • Practice problems involving vector cross products in three-dimensional space
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Students studying physics, particularly those learning about vector mathematics and cross products, as well as educators seeking to clarify the right-hand rule concept.

belvol16
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Homework Statement


The direction of vectors A and B are given below for several cases. For each case, state the direction of A X B.
a) A points east, B points south.
b) A points east, B points straight down.
c) A points straight up, B points north.
d) A points straight up, B points straight down.

Homework Equations


Using the right hand rule.

The Attempt at a Solution


So, I've tried to use the right hand rule but I am not sure if I am using it properly. (I haven't taken multivariable calculus yet so I struggle with dot products and vector cross products). I used my pointer finger as my x-axis, middle finger as my y-axis, and thumb as my z-axis.
a) I found that the vector points into the page. I put my index finger towards the east and middle finger south and found that my thumb pointed into my page.
b) I guess I'm not sure if pointing straight down is different than pointing south. If pointing straight down is the same as south, then b) points into the page as well.
c) I'm a little bit confused. I took both my index finger and middle finger and pointed them up and found the resultant vector points into the page.
d) I stuck my pointer finger up and middle finger down and found that the resultant vector points into the page.
I guess I don't quite understand how all of these vectors point into the page or if I'm doing something wrong. I've watched a few other tutorials using a method where you curl your fingers, but I didn't quite understand how those worked.
Any help is greatly appreciated.
 
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I think you should view it as a map laying on a table. So there are three orthogonal axes - (1) east - west, (2) north-south, (3) up-down. So down is not in the same direction as south. So I would use up-down instead of into and out of the page, because it is less confusing.
 
I agree with phyzguy. Imagine that you are standing outside on level ground. N, S, E, and W would be directions parallel to the ground. "Straight up" would be vertically upward, perpendicular to the ground. "Straight down" would be vertically downward, perpendicular to the ground.
 
I never used my fingers on the right hand rule for a vector cross-product. Instead, I envision a jar with a lid with a right-hand screw (right-hand is standard on all jars), and which way the cap moves (up or down) when you rotate it=e.g. rotating one vector into the other.
 

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