College Physics with MasteringPhysics 7th Edition by Jerry Wilson,Anthony Buffa,Bo Lou

Exercise 120

A simple pendulum has a length of 0.75 m and a bob with a mass of 0.15 kg. The bob is released from an angle of 25° relative to a vertical reference line (Fig.). (a) Show that the vertical height of the bob when it is released is h = L (1 - cos 25°). (b) What is the kinetic energy of the bob when the string is at an angle of 9.0° (c) What is the speed of the bob at the bottom of the swing (Neglect friction and the mass of the string.)

FIGURE A pendulum swings See Exercise.