Conservation of forces and poetential energy

[MEAHH]

conservation of forces and poetential energy!

Homework Statement

a potential energy function for a 2d force is of the form U=3x^3y-7x. find the force that acts at the piont (x,y).

Homework Equations

U=3x^3y-7x

The Attempt at a Solution

how do i do this? tahe the derivative?

 

[kamerling]

Homework Statement

a potential energy function for a 2d force is of the form U=3x^3y-7x. find the force that acts at the piont (x,y).

Homework Equations

U=3x^3y-7x

The Attempt at a Solution

how do i do this? tahe the derivative?

Yes. You might want to reread what your textbook says about the gradient of the potential energy function.

 

[MEAHH]

ok so i took the derivatives with respect to x and y
d/dx=9x^2y-7 and d/dy=3x^3
what do i do now? Subtract then, this chapter in my book doesn't talk about the gradient.

 

[kamerling]

The gradient is the vector idU/dx + jdU/dy (in two dimensions)
see also http://en.wikipedia.org/wiki/Gradient"