The Laws of Motion of a Cylinder, &c. 276 
In order to compare this force with gravity, it muft 
be remembered, that if a body begin to, afcend 
with an “aed velocity = 2, it will move through 
a {pace — —; therefore, if the force of gravity be 
=: 
denote: by the weight of the Cylinder, we have 
as p a ::dqfg: wien £98" — the refiftance oppofed 
to the motion of the waa Pee in the data, 
which retarding force is = the refiftance of the 
obftacle exerted on the furface g— the weight of 
the folid, and therefore the whole refiftance == 
a fan +dqfg. But if equal forces act on dif- 
rs 
ferent furfaces, being uniformly applied to every 
point of each, the effects produced will be as the 
furfaces, confequently, as g:e :: dafen” ef 
4rs . 
dqfg: UE + dqfe = the refiftance given 
a ge 
by ‘the Obftacte to the Cylinder of the Problem. 
But the difference of this refiflance, and the force 
arifing from the fum of the weights of the Block 
and Cylinder, expreffes the retarding force which 
conftantly acts on the fyftem that penetrates the 
Obftacle, and is = Soy dqgfe—dqec—a, 
which quantity may be called h, ‘and it may be 
here remarked that f is always affirmative, becaufe 
M m 2 a negative 
