64 FALLING BODIES. 



129. Laws of Falling Bodies. These formulas 

 may be translated into ordinary language as follows : 



(1.) The velocity of a freely falling body at the end of 

 any second of its descent is equal to 32.16 ft. (9.8 m.) mul- 

 tiplied by the number of the second. 



(2.) The distance traversed by a freely falling body 

 during any second of its descent is equal to 16.08 ft. (4.9 m.) 

 multiplied by one less than twice the number of seconds. 



(3.) The distance traversed by a freely-falling body 

 during any number of seconds is equal to 16.08 ft. (4.9 m.) 

 multiplied by the square of the number of seconds. 



130. For Bodies Rolling Down an Inclined 

 Plane. If the body be rolling down an inclined plane 

 instead of freely falling, of course the increment of velocity 

 will be less than 32.16 ft. The formulas above given may 

 be made applicable by multiplying the value of g by the 

 ratio between the height and length of the plane. 



131. Initial Velocity of Falling Bodies. 



"We have been considering bodies falling from a state of 

 rest, gravity being the only force that produced the motion. 

 But a body may be thrown downward as well as dropped. 

 In such a case, the effect of the throw must be added to 

 the effect of gravity. It becomes an illustration of the 

 first case under Composition of Forces ( 80), the resultant 

 being the sum of the components. If a body be thrown 

 downward with an initial velocity of fifty feet per second, 

 the formulas will become v = gt + 50 ; s = J# (2tl) 

 -f 50 ; S = \t* + 50t. 



132. Ascending Bodies. In the consideration of 

 ascending bodies we have the direct opposite of the laws of 

 falling bodies. When a body is thrown downward, gravity 



