Physical Science

The Physics of a Yo Yo

Simplified: The turning motion of your wrist applies rotational inertia to the axle and bulbs. Inertia builds (stored as angular momentum) as the string unwinds. When the yo-yo string is fully extended, friction acts between the string and axle to…
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Biography of Stephen Hawking

Stephen Hawking (1942-) is a retired Cambridge theoretical physicist. He is best known for his popularization of black hole and cosmological research, as well as his struggle with amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease), which has left him…
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Understanding Cosmic Inflation

Cosmic inflation is a well supported theory that states the early universe expanded exponentially resulting in several observable consequences. It is important to define the “early universe,” as different branches of physicists and cosmologists will use separate time scales. The…
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Force Concept Explained

Force like any physical concept is best explained by use of familiar examples. Technically speaking, force represents the change per time of momentum, i.e., a combination of mass [the mount of “stuff”], speed or direction, as that time interval becomes…
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