By Walter Lewin | Physics I: Classical Mechanics Lecture 7 of 35
This lecture explores weight, perceived gravity, weightlessness, free fall, and zero perceived gravity in orbit. An object is swirled around on a string in a vertical plane. The tension in the string is evaluated when the object is at the top and when it is at the bottom of its circular trajectory. Objects in free fall as described as weightless: Exploring the weight of a tennis ball being tossed in the air, and of a bottle of water in Professor Lewin's hands when he jumps off a table. The bottle and Lewin are in free fall, thus both are weightless.
This course is a first-semester freshman physics class in Newtonian Mechanics, Fluid Mechanics, and Kinetic Gas Theory. In addition to the basic concepts a variety of interesting topics are covered in this course: Binary Stars, Neutron Stars, Black Holes, Resonance Phenomena, Musical Instruments, Stellar Collapse, Supernovae, Astronomical observations from very high flying balloons (lecture 35), and you will be allowed a peek into the intriguing Quantum World.
