(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Find the magnitude of the vector product w ⃗x u, where w=<1,0,1> and u=<1,1,0>.

2. Relevant equations

||w x u|| = ||w|| ||u|| sin θ

cos θ = [itex]\frac{w.u}{||w|| ||u||}[/itex]

3. The attempt at a solution

w ⃗x u ⃗= -i ̂+j ̂+k ̂

‖||w ⃗x u|| ⃗ ‖= √3

but

cosθ= (w ⃗∙ u ⃗)/(‖||w|| ⃗||u||) ⃗ ‖ = 1/(√2 √2) implying ⟹ θ=[itex]\pi[/itex]/4

which then makes

‖||w ⃗x u|| ⃗ ‖= ‖||w|| ⃗||‖‖u|| ⃗sinθ

become

‖||w ⃗x u|| ⃗ ‖= √2 √2 sin〖[itex]\pi[/itex]/4

or the sqrt(2).

What's wrong here?

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Magnitude of Cross Product Mismatch

**Physics Forums | Science Articles, Homework Help, Discussion**