Book Description

Excerpt from Principles of Physics, Designed for Use as a Textbook of General Physics When a man exerts his muscles in moving a body or in pushing or pulling a body which he cannot move, he is con scious of the exertion of force. In many cases, as when he bends a spring or sustains a weight, he interprets his sensa tion by saying, that the body against which he acts exerts a force in the opposite direction to the one which he is exerting and of equal magnitude. He further believes that the body, when in the same position or condition, is still exerting a force, even though he does not directly perceive the counter acting force. He thus feels willing to use bodies in certain conditions or positions as the means by which forces may be exerted. When a body is sustained in the air by the hand, the force exerted by the hand, as is shown by universal experience, is directed vertically upwards. The force which the body is assumed to exert in the opposite direction or vertically down wards, is called its weight. Universal experience has shown that the weight of a body depends on its size and on the material of which it is composed. If different bodies com posed of the same material and of equal volume are tested by A the hand, or.in any other way, it is found that their weights are equal. Two of these bodies will have the same weight as a body of the same material and of a volume double that of either one of them. By suitable. Combinations of equal weights, any one of which is selected as a unit, a scale of forces can be constructed. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.