Question

2. A rubber rope of length 8 m is hung from the
ceiling of a room. What is the increase in
length of the rope due to its own weight?
(Given : Young's modulus of elasticity of
rubber = 5 x 100 Nm- and density of rubber =
1.5 x 109 kgm and g = 10 ms 2)
1) 1.5 mm
2) 6 mm
3) 24 mm
4) 96 mm​

Answer 1

Answer:

Correct option is

D

96mm

Weight of rubber W=mg=ρALg=8×1.5×10

3

×A×g , where A is cross sectional area.

Elongation due to own weight is half of the elongation due to point load.

ΔL=

2AY

WL

=

2A×5×10

6

8×1.5×10

3

×A×L×g

=96 mm