Question

A 5 metre long wire is fixed to the ceiling. A weight of 10 kg is hung at the lower end and is 1 metre above the floor. The wire was elongated by 1 mm. The energy stored in the wire due to streching is

• A. Zero
• B. 0.05 joule
• C. 100 joule
• D. 500 joule

Answer 1

Answer: (B)

0.05 joule

Answer 2

$W = \frac { 1 } { 2 } \times F \times l = \frac { 1 } { 2 } m g l$

$= \frac { 1 } { 2 } \times 10 \times 10 \times 1 \times 10 ^ { - 1 } = 0.05 \mathrm {~J}$