Show the time derivative of the expectation value of momentum is equal to (up to a minus sign) the expectation value of the x-derivative of the potential energy.

Gam radio signals can usually be heard behind a hill, but fm often cannot. that is, am signals bend more than fm. explain. (radio signals, as we shall see, are carried by electromagnetic waves whose wavelength for am is typically 200 to 600 m and for fm about 3 m.)

At what point the certain object feels zero garvitational force between earth and the moon. take the required information from the book. required: distance away from earth or moon

Why is alternating current more effective at long–distance travel than direct current? a. the power lines are made out of conductors. b. transformers increase or decrease voltage as needed. c. the ac generator is more efficient. d. ac has lower voltage than dc.