Understanding Angular Momentum: A Brief Explanation of Vector Cross Products

[queenspublic]

When doing Angular Momentum, how is it that 2.0(2.12i + 2.12j) x (-3.863i - 1.035j) is equal to 2.0[-2.194k + 8.189k]?

 

[tiny-tim]

'cos i x j = k and j x i = -k (and ii = jj = 0)

 

[queenspublic]

'cos i x j = k and j x i = -k (and ii = jj = 0)

I don't understand.

cos i x j = k ?

So cos 2.12i x 2.12j = -2.194k ?

Please explain it in numbers. How do I get -2.194k + 8.189k ?

 

[tiny-tim]

I don't understand.

cos i x j = k ?

So cos 2.12i x 2.12j = -2.194k ?

he he :rofl:

no, I meant because i x j = k

 

[queenspublic]

he he :rofl:

no, I meant because i x j = k

O! I get it! Thanks.