Question

A wire elongates by 9 mm when a load of 10 kg is
suspended from it. What is the elongation when its
radius is doubled, if all other quantities are same as
before ?​

Answer 1

Answer:

Y= F/πr^2 . l/∆l

or r^2 ∆l = Fl/πY = constant

r1^2∆l1 = r2^2 ∆l2

given, ∆l1 = 9mm, r2 = 2 r1

r1^2 × 9mm = 4r1^2

or ∆l2 = 9/4 = 2.25 mm.