How many moles of water, h2o, contain 2.0_1022 molecules of water?

What are similarities and differences between refraction, reflection, diffraction and absorption?

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.

Thermal radiation gets its name because