I N C 



Cor. 9. If a body be supported on two 

 inclined planes, the pressures on A B, B C 

 and the weight of the body are represent- 

 ed by sin. C B E, sin. A B D, and sin. C B A 



respectively. 



II. Inclined planes, motion of bodies down. 



1. The force which accelerates or retards a body's motion upon an in- 

 clined plane, is to the force of gravity, as the height of the plane to its 

 length. 



Hence if g 32% feet, accelerating force = C j or if * = plane's 



it 



inclination, accelerating fone = g X sin. . 



Cor. 1. Hence if in the formulae for the rectilinear descent of bodies 

 (see Motion J we substitute g X y- or & * s ^ n - ** ^ r ^ we sna ^ have, 

 if the body descends from rest, 



v = - X g t = sin. * X g t. 



- __ _ _ 

 "~ H A 2g ~ Sg-Xsin. *' 



Cnr. 2. The velocity acquired in falling down the whole length of an 

 inclined plane varies as ^H- 



Cor. 3. The time of descent down the whole length of an inclined plane 

 varies as '. Or if the inclination be given, i.e. if H varies as L, T va- 



A/H 



ries as V L- 



2. If chords be drawn in a circle from the extremity of that diameter 

 which is perpendicular to the horizon, the velocities which bodies acquire 

 by falling down them are proportional to their lengths ; and the times oi 

 descent are equal. 



Cor. The times of descent down chords indifferent circles are a^ tlie 

 iquare roots of the diameters. 

 H7 



