Before the invention of modern electronics and high-speed cameras, scientists use simple physics to measure the speed of gun bullets. One method involves firing the bullet horizontally into a pendulum to make the pendulum swing. Supposedly the 7.45-gram bullet is shot into a 1.000-kg static pendulum suspended by a thin thread of 70.0 cm long. The bullet enters the pendulum and stays in it. The pendulum then swings through a maximum angle of 60.0 degrees (from the vertical direction.)

1. What is the potential enginery change of the system during the swing in the unit of joule?
2. What is the KE of the system at the beginning of the swing (right after the collision)?
3. What is the magnitude of the system’s momentum right after the collision?
4. What is the magnitude of the bullet’s momentum when it hits the pendulum? Answer
5. What is the speed of the bullet v0, when it hits the pendulum?