Millikan Egbert A., Gale Henry G. Practica Physics

New York: Ginn and Company, 1922. — 572 p.; il.A certain amount of knowledge about familiar things comes to us all very early in life. We learn almost unconsciously, for example, that stones fall and balloons rise, that the teakettle stops boiling when removed from the fire, that telephone messages travel by electric currents, etc. The aim of the study of physics is to set us to thinking about how and why such things happen, and, to a less degree, to acquaint us with other happenings which we may not have noticed or heard of previously. Most of our accurate knowledge about natural phenomena has been acquired through careful measurements. We can measure three fundamentally different kinds of quantities, length, mass, and time, and we shall find that all other measurements may be reduced to these three. Our first problem in physics is, then, to learn something about the units in terms of which all our physical knowledge is expressed.