5

The Lifting Force, Flifting

Gravity, Weight, and the Lifting Force

Gravitational attraction acts on the mass of all matter, pulling any two objects together. Normally, we perceive only the pull of one close-by massive object, the earth, but in fact all objects attract all others gravitationally (trivia: two 10 lb objects 1 foot apart exert a gravitational attraction force of about 1 billionth of a pound on each other). By convention, the force developed due to the gravitational pull of the Earth is called weight, and many texts therefore give it the symbol w. In this book, a force is a force regardless of its origin, and so for consistency weight will be expressed as Fw.

Every person has learned through experience to gauge how hard it might ...

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