The potential energy function U(x, y)=A[(1/x2) + (1/y2)] describes a conservative force, where A>0.
Derive an expression for the force in terms of unit vectors i and j.

Explanation:

You have the following potential energy function:

          (1)

A > 0 constant

In order to find the force in terms of the unit vectors, you use the gradient of the potential function:

        (2)

Then, you replace the expression (1) into the expression (2) and calculate the partial derivatives:

(3)

The result obtained in (3) is the force expressed in terms of the unit vectors, for the potential energy function U(x,y).

absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum whereas.

emission spectra have spikes in the spectra due to atoms releasing photons at those wavelengths.

explanation:

a person with a mass of 106kg has a weight of 1060n