MOVING roUCK. 
6-i 
Cases of diffi- motion of o and p must be equal to the sum of the quantities ot 
doctiuKs^o'f >^otion of m and n. But let both beams be at rest, and let the 
mowiig force, pressure of 2 be applied for a given time to C, to generate velo- 
city in 0 andp; a pressure of 3 will be required to be applied 
to A for an equal time, and through an equal space, to gene- 
rate an equal velocity in TO. The generating forces, therefore, 
.tie as 2 to 3, although the quantities of motion generated by 
these forces are equal. 
5 . Let G (tig. 5.) be the centre of gravity of two bodies, A i 
and B, connected by an elastic rod, at rest, but free to move in , 
any direction ; and let a given quantify of motion be commu- | 
riicated at any point, D, in a direction at right angles to the rod, j 
Tvir. Vince has demonstrated that the velocity of G will be the i 
same wherever the motion is communicated*; that is, if a 
given force be applied, or quanlitv of motion communicated at 
G, a progressive motion of the mass, without any rotatory ' 
motion, will be the result ; but if the same force be applied at l 
any other point D, we shall have the same progressive motion, j 
and a rotatory motion besides. i 
Is that rotatory motion produced without force ? 
Examples of Motion destroyed, and of Motion transferred from li 
one hoey to another. 
(5. If the weight of the ball. A, (fig. 6 .) be to that of B, | 
as 2 to 1 , and if they move in opposite directions with veloci- 
ties reciprocally as their weights, and strike at (he same instant If 
the ends of the spring. S. If the strength of the spring be I' 
such, that the brdls shall be at rest when its ends are brought to v 
qieet ; they will meet at E, DE being equal to 2 CE. Here l 
tlie effect produced is the compression of the spring. But | 
though the quantity of motion of A is equal to that of B, the '' 
portion of the effect produced by A, is less tliau that which is I! 
produced by B. 1 1 
if we substitute for B a ball equal in weight and velocity to ^ 
• J'hitopliical Trarsactioas, vol. 70, p. 651. 
A, f 
