A steel cable is used to support an elevator cage at the bottom of a 2,000 ft deep mineshaft. A uniform normal strain of 250 uin/in is produced in the cable by weight of the cage. At each point, the weight of the cable produces an additional normal strain that is porportional to the length of the cable below the point. If the total normal strain in the cable at the cable drum ( upper end of the cable) is 700 uin/in,
Determine :
A) The strain in the cable at a depth of 500 ft.
B) The total elongation of the cable.