7. A boy lifts a 2. 2-kg book from his desk, which is 0. 80 m high, to a bookshelf that is 2. 10 m high. What is the potential energy of the book-Earth system relative to the

desk when the book is on the shelf?

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)