Why does a moving object come to a stop on a frictional surface?

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b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle

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.