Answer
a. $m_0$ is the mass of the object with $v=0$ or at a speed of 0.
b. The physical significance is that as the object approaches the speed of light by increasing its speed or from the left, its mass approaches $\infty$.
Work Step by Step
a. The function $m(v)$ is the mass of an object as a function of v. Therefore, $m_0$ is the mass of the object with $v=0$ or at a speed of 0.
b. From Fig. Ex-32 given in the problem, $m$ approaches $\infty$ as $v$ approaches c from the left. Thus,$ \lim_{v \to c^-} m(v) = \infty$. The physical significance is that as the object approaches the speed of light by increasing its speed or from the left, its mass approaches $\infty$.
