A ballistic pendulum is used to measure the speed of bullets. It comprises a heavy block of wood of mass M suspended by two long cords. A bullet of mass m is fired into the block horizontally. The block, with the bullet embedded in it, swings upward (Fig. P10.70). The center of mass of the combination rises through a vertical distance li before coming to rest momentarily. In a particular experiment, a bullet of mass 40.0 g is fired into a wooden block of mass 10.0 kg. The block-bullet combination is observed to rise to a maximum height of 20.0 cm above the block's initial height.
a. What is the initial speed of the bullet?
b. What is the fraction of initial kinetic energy lost after the bullet is embedded in the block?
