- #1
Destroxia
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- 7
Homework Statement
Find the work done by the three-dimensional inverse-square field
## F(r) = \frac {1} {||r||^3} r ##
on a particle that moves along the line segment from P(6, 2, 3) to Q(4,2,4)
Homework Equations
## \int_C F \bullet dr = \int_a^b f(h(t), g(t)) \sqrt {(\frac {dx} {dt})^2 + (\frac {dy} {dt})^2} = \int_a^b f(h(t),g(t)) ||\vec r'(t)|| dt##
The Attempt at a Solution
I cannot figure out where to start. I've been generally confused by line integrals the entire section. The only relationship I can see is with the 3rd equation I provided in the relevant equations where we have a magnitude ##||\vec r'(t)||##. But then what would be the function F? Is it the ##\frac {1} {||r||^3} r##? But that is a function of F(r), so I'm not sure how this changes the dynamics of the problem...? The most I could thing of would be along the lines of
## \int_C F \bullet dr = \int_a^b f(h(t),g(t)) ||\vec r'(t)|| dt##
## \int_C F \bullet dr = \int_a^b \frac {r} {||r||^3} ||\vec r'(t)|| dt ##
but now we have a function of r AND t inside this integral, but the integral is with respect to t, so could I just pull the function of r out?
## \int_C F \bullet dr = \frac {r} {||r||^3} \int_a^b ||\vec r'(t)|| dt ##
but then what is the function for r(t), I don't understand parameterization very well, and I'm not sure if I'm supposed to make some kind of parametric substitution?