Which would show an example of how physical changes are reversible? cutting a gold bar in two pieces and then putting the pieces next to each other
burning a match and then relighting it
melting tin and then cooling it into a mold
combining sodium and chlorine to make the new material of table salt

A100 kg running back runs at 5m/s into a stationary linebacker. it takes 0.5 for the running back to be completely stopped

With the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 1.90

What are some properties of transverse waves?