(Calc 3) Finding mass of a wire using line integral

NWeid1
Messages
81
Reaction score
0

Homework Statement


Find the mass of a wire in the shape of the parabola y=x2 for 1 \leq x\leq2 and with density p(x,y)=x.

Homework Equations


The Attempt at a Solution



I just want to make sure I am setting this integral up right. Here is what I did:

I parameterized the equation to x=t, y=t2
and then got \int xds from 1 to 2.
then I set ds = \sqrt{1+4t^2}*dt

so I would have

\int t*\sqrt{1+4t^2}dt from 1 to 2. Correct, or no?
 
Last edited:
Physics news on Phys.org
NWeid1 said:

Homework Statement


Find the mass of a wire in the shape of the parabola y=x2 for 1 \leq x\leq2 and with density p(x,y)=x.

Homework Equations





The Attempt at a Solution



I just want to make sure I am setting this integral up right. Here is what I did:

I parameterized the equation to x=t, y=t2
and then got \int xds from 1 to 2.
then I set ds = \sqrt{1+4t^2}*dt

so I would have

\int t*\sqrt{1+4t^2}dt from 1 to 2. Correct, or no?

Yes.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top