Silly question about Cross-Product

Thread starter Saladsamurai
Start date Mar 3, 2008

AI Thread Summary

To find angular momentum using the formula r x mv, the mass (m) can be factored out of the cross product. It is not necessary to distribute the mass to the vector v before calculating the determinant; instead, you can multiply the result of r cross v by m afterward. The equation r x (mv) simplifies to (m r) x v, which is equal to m (r x v). Thus, the mass can be treated as a scalar multiplier in the context of the cross product. Understanding this relationship clarifies the calculation of angular momentum.

Mar 3, 2008

Saladsamurai

I just forget the rule here.

I am finding angular momentum by using r x mv

If I am using the determinant to evaluate r cross v, where does the mass come in? Do I just mulyiply the result of r cross v by m?

Or do I distribute m to my vector v and then use those values inside the determinant?

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Mar 3, 2008

CompuChip

Science Advisor

Homework Helper

It doesn't matter. m is just a number, so
r x (m v) = (m r) x v = m (r x v)

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