Shing
- 141
- 1
Hi guys,
recently I am reading Kleppner's Mechanics
about center of mass,
well, I am always a fairly fast learner,
but I really got stick here.
you see,
in the page 119
example 3.3 (in short, a rod with nonuniform density )
let Q(x) be the function density of location vector
it said
M=\int{dm}
\int{dm}=\int{Qdx}
however, when I do the calculation on my own.
dm=Qdx+xdQ
then intergrate both sides
\int{dm}=\int{Qdx}+\int{xdQ}
so should there be Int(xdQ) ?
2.) I just out of the blue thinking of during my calculation, what if I come across a vector times itself two times?
as for just one time, then it is a dot product,
but, a scalar simply can't dot product with a vector!
so what is the meaning of {v}^3? (v is a vector)
Thanks for your reading!
recently I am reading Kleppner's Mechanics
about center of mass,
well, I am always a fairly fast learner,
but I really got stick here.
you see,
in the page 119
example 3.3 (in short, a rod with nonuniform density )
let Q(x) be the function density of location vector
it said
M=\int{dm}
\int{dm}=\int{Qdx}
however, when I do the calculation on my own.
dm=Qdx+xdQ
then intergrate both sides
\int{dm}=\int{Qdx}+\int{xdQ}
so should there be Int(xdQ) ?
2.) I just out of the blue thinking of during my calculation, what if I come across a vector times itself two times?
as for just one time, then it is a dot product,
but, a scalar simply can't dot product with a vector!
so what is the meaning of {v}^3? (v is a vector)
Thanks for your reading!
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