Question

A rubber cord 10 m long is suspended vertically. How much does it stretch under its own weight (Density of rubber is 1500 kg/m³, Y = 5×10⁸ N/m², g = 10 m/s²)

• A. 15×10^­–4 m
• B. 7.5×10^­–4 m
• C. 12×10^­–4 m
• D. 25×10^­–4 m

Answer 1

Answer: (A)

15×10^­–4 m

Answer 2

$l = \frac { L ^ { 2 } d g } { 2 Y } = \frac { ( 10 ) ^ { 2 } \times 1500 \times 10 } { 2 \times 5 \times 10 ^ { 8 } } = 15 \times 10 ^ { - 4 } \mathrm {~m}$