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

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?

How much energy is released when a ${\text{µ}}^{-}$ muon at rest decays into an electron and two neutrinos? Neglect the small masses of the neutrinos.

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.

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

If a ${\Sigma }^{+}$ at rest decays into a proton and a ${\pi }^0$, what is the total kinetic energy of the decay products?