Khan Academy
Khan Academy: Newton's Law of Gravitation: Gravity for Astronauts in Orbit
Video lecture explains why astronauts appear weightless despite being near the Earth. [7:12]
Khan Academy
Khan Academy: Cepheid Variables: Why Gravity Gets So Strong Near Dense Objects
Find out why gravity gets so strong near dense objects. [8:13]
NPR: National Public Radio
Npr Videos: Skunk Bear: How Eclipses Changed History
Newton and Einstein had big ideas but needed an eclipse to prove them. And scientists are still pursuing secrets of the universe one eclipse at a time. [6:09]
Khan Academy
Khan Academy: Gravity for Astronauts in Orbit
Why do astronauts appear weightless despite being near the Earth? Sal Khan answers this question in this video. [7:11]
The Kid Should See This
Tksst: The Hammer Feather Drop in the World's Biggest Vacuum Chamber
Brian Cox visits NASA's Space Power Facility to demonstrate what happens when a bowling ball and a feather are dropped together under the conditions of space. [4:41]
Khan Academy
Khan Academy: Mass and Weight Clarification
Sal Khan explains the difference between mass and weight. [10:40]