Question

An elastic string gas length a when tension in it is 4N. Its length is b when tension is 5N. On subjecting the string to a tension of 9N its length will be?

Answer 1

tension is a force
F1/ F2=l1/l2
4/5=a/b

let length x when tension is 9
9/5= x/b
x= 9b/5
hope this will help you

Answer 2

Answer:

Explanation:

let x1 and x2 be the extension with 4N and 5N respectively.

then the eqns. would be:

4 = k * x1  and  5  = k * x2

and let l be the natural length of the wire.

Hence,

x1 + l = l1

and

x2 + l = l2  

put x1 and x2 values in Tensions after dividing them respectively:

Therefore,

4/5 = x1/x2 = > (l1 – l)/(l2 – l)

4l2 – 4l = 5l1 – 5l

l = 5l1 – 4l2

hence would be the nautral length.