The reduced mass of a two-body system is 2.1 u.If one of the masses is 3 u,then what is the mass of the second body?
A)5 u
B)7 u
C)9 u
D)6 u
E)4 u

Question

Quizplus · Accepted Answer

The reduced mass $\mu$ of a two-body system with masses $m_1$ and $m_2$ is given by $\mu = \frac{m_1m_2}{m_1 + m_2}$. Given $\mu = 2.1$ u and $m_1 = 3$ u, solving the equation $2.1 = \frac{3m_2}{3 + m_2}$ for $m_2$ yields $m_2 = 7$ u.

The Reduced Mass of a Two-Body System Is 2