136 OUTLINES OF NATURAL PHILOSOPHY. 



SECT. VII. 



ROTATION OF BODIES. 



Rotation about a Fixed Axis. 



216. LET A, B, C, D, &c. (fig. 13.) be a sys- 

 tem of bodies in one plane, so connected as to be 

 immoveable in respect of one another, but moveable 

 about an axis at right angles to the plane, and 

 passing through a given point S ; let , b, c 9 d, be 

 their distances respectively from S ; and let a force 

 act on one of the bodies A, such that if A were 

 unconnected with the system, it would receive the 

 velocity u 9 in a direction at right angles to the ra- 

 dius a ; let v be the velocity which it actually ac- 

 quires when it makes a part of the system ; 



That is, if each body be multiplied into the square 

 of its distance from the axis of rotation, the sum 

 of all these products, is to the product of A, into 

 the square of its distance from the same axis, as 

 the velocity which A would have had if it had 



beer? 



