Ibelieve that our solar system formed by the same process as star formation. a huge cloud of dust and gas collapsed and condensed. gravity pulled matter into the center core, nuclear fusion began, and our sun was created. remaining matter and gas clumped together to form the planets. i believe in the

big bang theory
condensation theory
nebular theory
oscillating theory

the first american roller coaster was the mauch chunk switchback railway, built in the mountains of pennsylvania in the mid-1800s. the track, originally built to send coal to a railway, was reconfigured as a "scenic tour."

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.