Question

The Young's modulus of a rope of 10 m length and having diameter of 2 cm is 20.0 x 10¹¹ dyne/cm². If the elongation produced in the rope is 1 cm, the force applied on the rope is

(a) 6.28 x 10⁵ N 

(b) 6.28 x 10⁴ N

(c) 6.28 x 10⁴ dyne 

(d) 6.28 x 10⁵ dyne

Answer 1

Correct option (b) 6.28 x 10⁴ N

Explanation :

Here, Length of the rope, L = 10 m

Diameter of the rope, D = 2 cm

Radius of the rope, r = D/2 = 1 cm = 10^-2 m

Young's modulus of the rope

Elongation of rope,