Q values and thresholds in code

You will write three functions for nuclear reactions.

The idea. The Q value is the mass before minus the mass after, times $931.494$ MeV/u. For a target at rest, the threshold is $|Q|\,\dfrac{m_a + m_X}{m_X}$. From rest, product $1$ takes the energy $Q\,\dfrac{m_2}{m_1 + m_2}$.

Your tasks.

1. In q_value, return $Q$ in MeV for the lists of masses before and after, in u.
2. In threshold, return the threshold energy in MeV for a negative q, a projectile mass m_a and a target mass m_x.
3. In share, return the kinetic energy in MeV of the product of mass m1, when the two products have masses m1 and m2 and the total energy is q.