Cross Products Help

  • #1

Homework Statement



Given two vectors A⃗ = 4i + 7j and B⃗ = 5i − 2j , find the vector product A⃗ × B⃗ (expressed in unit vectors).
Express your answer in terms of the unit vectors i, j, and k.

Homework Equations





The Attempt at a Solution



I know how to cross and multiply them but they don't give the z component so I assumed it was zero

This is what I got

0i + 0j - 43k

Why is that wrong ?, I'm doing this online assignment and it keeps telling me, "The correct answer does not depend on i,j and k"
 

Answers and Replies

  • #2
21,488
4,863

Homework Statement



Given two vectors A⃗ = 4i + 7j and B⃗ = 5i − 2j , find the vector product A⃗ × B⃗ (expressed in unit vectors).
Express your answer in terms of the unit vectors i, j, and k.

Homework Equations





The Attempt at a Solution



I know how to cross and multiply them but they don't give the z component so I assumed it was zero

This is what I got

0i + 0j - 43k

Why is that wrong ?, I'm doing this online assignment and it keeps telling me, "The correct answer does not depend on i,j and k"
You did it right. They probably just want -43k.

Chet
 
  • #3
You did it right. They probably just want -43k.

Chet

Yeah, I guess they just wanted -43k with the hat on top. Stupid system, now I lost 3% for each "wrong" attempt :mad:

Thanks for your reply
 

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