An engineering student found that the Youngs modulus of an alloy was 2.8 x 10^11 Pa. The 1.5m wire of the allow increased in length by 0.24% during an experiment. Calculate the stress on the wire.

The Youngs modulus of a material is = Stress / Strain. Therefore, the stress of an object is the strain multiplied by the Youngs modulus. We know that strain is the change in length (or extension) divided by the original length.  Which in this case, is  (1.5 * 1.0024 )m  /  1.5m - notice the units cancel. Multiplying this by 2.8x 10^11Pa (YM) will give us a stress of 6.7 x 10^8 Pa. Notes: 0.0024 is 0.24% written as a decimal, so an increase in 0.24% is 1.0024 multiplied by the original length.