Explain your problem of
Federalism
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That is more of a History of English question.

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 answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this