Question

3. The proportional limit of steel is 8 x 10 N/m2 and
its Young's modulus is 2 x 1011 N/m2. The
maximum elongation, a one metre long steel wire
can be given without exceeding the proportional
limit is
(1) 2 mm
(2) 4 mm
(3) 1 mm
(4) 8 mm​

Answer 1

Answer:

Maximum elongation is 4mm

Explanation:

Young's modulus =

$2 \times 10 {}^{11}$

Propotional limit or stress

$8 \times 10 {}^{8}$

Hence

$youngs \: modulus \: = \frac{srtess}{strain}$

$2 \times 10 {}^{11} = \frac{8 \times 10 {}^{8} }{ \frac{l}{1} }$

$l = \frac{8 \times 10 {}^{8} }{2 \times 10 {}^{11} }$

L = 4 mm