The elastic limit of steel is 8 × 108 N m-2 and its Young modulus 2 × 1011 N m-2. Find the maximum elongation of a half-meter steel wire that can be given without exceeding the elastic limit.
2 mm
Elastic limit here means the maximum stress a wire can hold.
Hence, maximum stress, 
Young modulus of the metal, 
Let the strain be 
. The length of the wire is 
. Let the elongation be 
.
We know,
—————-(1)
And 
—————-(2)
From (1) and (2)
1