THE MECHANICAL POWERS. 283 



RULE. Add the squares of the height and the base, and 

 the square root of their sum will be the length. 



EXAMPLE. What is the length of an inclined plane the 

 base of which is 20 feet and its height 12 1 



SOLUTION. 400, square of base, + 144, square of height, 

 = y 544 = 23.32 feet. Am. 



To fond the base when the length and height are given. 



RULE. Subtract the square of the height from the square 

 of the length, and the square root of the remainder will be 

 the base. 



EXAMPLE. What is the base of an inclined plane, whose 

 height is 10 feet, and length 25 ? 



SOLUTION. 625, square of length, 100, square of 

 height, = y 525 = 22.91 feet. Ans. 



To find tJie pressure of a weight on an inclined plane when 

 raised by its equivalent power. 



RULE. As the length is to the weight, so is the base to 

 the pressure. 



EXAMPLE. What is the pressure of 1000 Ibs. on an in- 

 clined plane, the length of which is 80 feet and the base 70 ? 



SOLUTION. 80 feet, length, : 1000 Ibs., :: 70 feet, base, 

 : 875 Ibs. Ans. 



NOTES. When the line of direction of the power is par- 

 allel to the plane, the power is least and the pressure 

 least. 



