Physics question

[Gibson486]

Given vectors A = -4.1 i + 8.5 j and B = 9.6 i + 6.7 j, determine the vector C that lies in the xy plane perpendicular to B and whose dot product with A is 20.0.

Am I suppossed take A and C and set it equal to 20? i know that B equals zero b/c two vectors perpindicular to each other always equal zero. How do i solve it?

 

[GoodToGo]

Originally posted by: Gibson486
Given vectors A = -4.1 i + 8.5 j and B = 9.6 i + 6.7 j, determine the vector C that lies in the xy plane perpendicular to B and whose dot product with A is 20.0.

Am I suppossed take A and C and set it equal to 20? i know that B equals zero b/c two vectors perpindicular to each other always equal zero. How do i solve it?

Heres what I think the answer should be:

Let C = x i + y j

If a vector is perpendicular to another, their dot product is zero.

So 9.6x + 6.7y =0

Also dot product with A is 20

-4.1x + 8.5y = 20

This is a simple system of linear equations. Solve for x and y to get your vector.

 

[zzzz]

goodtogo got it right....but where is the physics???? Its just a math Q.

 

[fizmeister]

This isn't really physics. It's more like a vector math problem.