A simple pendulum is made by attaching a small cup of sand with a hole in the

Question:

A simple pendulum is made by attaching a small cup of sand with a hole in the bot- tom to a 1.2-m-long string. The pendulum is mounted on the back of a small motorized car. As the car drives forward, the pendulum swings from side to side and leaves a trail of sand as shown in Figure P15.67. How fast was the car moving?

FIGURE P15.67 15 cm