Can we see the back side of the moon from earth?

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.

A10 kg box initially at rest is pulled 18 meters across a horizontal, frictionless surface by a 40 n force. what is the block’s final velocity over the 18 meters?

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?