Math Is Fun Forum

gourish

Member

Registered: 2013-05-28

Posts: 153

physics related i am posting it here since the math part is confusing

The work done on a particle of mass m by force=k*[x/(x^2+y^2)^3/2 i(cap)+y/(x^2+y^2)^3/2 j(cap)]
k is a constant and the particle is taken from (a,0) to (0,a) along a circular path of radius a about the origin in x-y plane is

well i let x^2+y^2=r^2 and then found the force as k[x/r^3 i(cap)+y/r^2 j(cap)]
the problem is i found in my course sheet that take x*dx+y*dy=r*dr now that is the MATH part and i am confused
P.S. bob here is that problem which i was discussing with u on my other post and any math+physicist please help me out

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"The man was just too bored so he invented maths for fun"
-some wise guy

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: physics related i am posting it here since the math part is confusing

hi gourish

Is this right ?

k is a constant and the particle is taken from (a,0) to (0,a) along a circular path of radius a about the origin in x-y plane is

I've changed a power 2 into 3 here.

Then I would say:

If the radius of the circle is constant then the term after the equals would be zero.  I'm a bit surprised the book would want to have r varying over time.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

gourish

Member

Registered: 2013-05-28

Posts: 153

Re: physics related i am posting it here since the math part is confusing

well i did not answer how the answer was found?

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"The man was just too bored so he invented maths for fun"
-some wise guy