CH. IX CENTRIFUGAL FORCE 1 43 



In the case of the loaded coach, the centrifugal 

 force, acting at a height of 5.5 feet, required to 

 balance the weight of the coach, 4000 pounds, with 

 a leverage of 2.5 feet, will be 1818 (4000X2.5 

 = 10,000, and 1 81 8 X 5-5= 10,000). This is the 

 force due to a speed of 16.5 miles an hour on a 

 curve of 50 feet radius, at which speed the coach 

 would be turned over. 



not t;2 



= 1818 or v l = 732 



32.2 x 5° 

 v — 27 feet per second or 16.5 miles per hour. 



It must be borne in mind that these are the 

 figures for a perfectly smooth road, level cross- 

 wise ; trifling depressions in the road causing lat- 

 eral swinging will overturn the coach at lower 

 speeds. 



In the familiar example of a horse galloping 

 round a circus ring, it will be noticed that the 

 horse's body is inclined toward the centre of the 

 circle at an angle which depends upon the velocity 

 with which he is moving ; the faster he goes the 

 more he leans. 



Another example is that of a bicycle moving 

 round the curve at the end of a cycling track. 



Since a man and his bicycle may be said 

 to form a single straight line from his head to 

 the point where the wheel touches the ground, 

 the angle of this line with the horizontal must 

 be such that the action of the centrifugal force 



