Problem 1.162

A horizontally flying bullet of mass \(m\) gets stuck in a body of mass \(M\) suspended by two identical threads of length \(l\) (Fig. 1.42 ). As a result, the threads swerve through an angle \(\theta\). Assuming \(m \ll M\), find: (a) the velocity of the bullet before striking the body; (b) the fraction of the bullet's initial kinetic energy that turned into heat.