Question

The potential energy of a pair of hydrogen atoms separated by a large distance x is given by U(x)=-C(subscript)6/x^6, where C_6 is a positive constant. What is the force that one atom exerts on the other? Is this force attractive or repulse?

I've taken the derivative of the equation and found it to be U(X)'= 6C_6/x^7
so the force should be inward/attractive. Is this all the info i need?

Answer 1

he potential energy of a pair of hydrogen atoms

Answer 2

the force F is is given by
F = -grad ( U )
Thus F = -C_6/x^7 and its attractive