The spectrum of the sodium atom is detected in the light from a distant galaxy. Use the Hubble law to calculate the distance of the galaxy from the earth.

The spectrum of the sodium atom is detected in the light from a distant galaxy. If the $590.0$-nm line is redshifted to $658.5$ nm, at what speed is the galaxy receding from the earth?

What is the total kinetic energy of the decay products when an upsilon particle at rest decays to $r^{+}+r^{-}$?

In which of the following reactions or decays is strangeness conserved? In each case, explain your reasoning.

(a) $K^{+}+{\mu }^{+}+{\nu }_{\mu }$

(b) $n+K^{+}\to p+{\pi }^0$

(c) $K^{+}+K^{-}\to {\pi }^0+{\pi }^0$

(d) $p+K^{-}\to {\Lambda }^0+{\pi }^0$