MOTION OF PROJECTILES. 



67 



= 1*25 seconds. The time of the ascent being 



known, the height which the body attains may be cal- 

 culated. The space which a body projected upwards 

 describes is diminished by gravity in the same manner 

 as that in which the same force increases the space tra- 

 versed by a body projected downwards. If the body is 

 projected with a velocity of 29 m *4, its height after three 

 seconds would be 3x 29 m *4, = 88 m *2, if there were no 

 gravity. But gravity moves the body downwards in three 

 seconds through 3 x3 x 4'9 = 44 m 'l, and the at- 

 tained height is therefore only 88*2 44-1 = 44 m *l. 



In this manner the heights may be calculated which 

 correspond to different velocities of projection. The 

 following small table exhibits a few values which are 

 connected in this manner, and in column 5 is shown a 

 tore simple method of calculating the heights. 



F 2 



