IMG_20190221_115536.jpg 38. The length of an elastic string is x meter when the tension is 8N and y meter when the tension is 10 N. The length in metre when the tension is 18 N is
stress=youngs modulas*strain
8/A=Y*(X-L)/L....................(1)
10/A=Y*(y-L)/L....................(2)
18/A=Y*(Z-L)/L....................(3)
(1)/(2)
solving we get L =5X-4y
(3)/(2)
9y-9L=5Z-5L
eliminating L
Z=5y-4X