80 



WELLS'S NATURAL PHILOSOPHY. 



would move but for the action of the two forces, which compel it to follow 

 the parabolic curve, a c. 



Fig. 52. 



h 



The mud sticks to the wheel, in the first instance, through the force of ad- 

 hesion ; but this force, being very weak, is overcome by the Centrifugal Force, 

 and the particles of mud fly off. The particles which compose the wheel it- 

 self would also fly otf in the same mamncr, were not the force of cohesion 

 which holds them together stronger than the Centrifugal Force. 



The Centrifugal Force, however, increases with the velocity 

 of revolution, so that if the velocitj' of the wheel were contin- 

 ually increased, a point would at last be reached, when tlie 

 Centrifugal Force would be more powerful than the force of 

 cohesion, and the wheel would then fly in pieces. In this 

 way almost all bodies can be broken by a sufficient rotative 

 velocity. Large wheels and grind- 



Under TThat 

 circumstances 

 will the (Jen- 

 trifugal Force 

 overcome the 

 Force of Cohe- 

 ■ionf 



Fig. 53. 



Btones, revolving rapidly, not infre- 

 quently break from this cause, and the 

 pieces fly off with immense force anci 

 velocity. 



"When we whirl a mop, the water 

 flies otf from it by the action of the 

 Centrifugal Force. The fibers, or 

 threads, which compose the mop, also 

 tend to fly off", but being confined at 

 one end, they are unable so to do. 

 They, therefore, assume a sphericiil 

 form, or shape. 



The fact that water can be made to 

 fly off from a mop, by the action of the 

 Centrifugal Force produced by whirling 

 it, has been most ingeniously applied 

 in a machine for drying cloth, called 



