A wire, of length 250 centimeters, and radius 0.3 millimeters is stretched by hanging on a weight of 12 kilograms, and the elongation produced is 8 milimeters. Calculate the value of Young's modulus for the wire.

I've never even heard of Young's modulus and it's not in my physics book. Any help?

Young's modulus is used in engineering mechanics to define what is essentially a spring constant for a material. It is defined as the ratio of stress to strain when a load is applied to the material. Stress is defined as the force divided by the cross-sectional area. The resulting strain of the material is defined as the ratio of the elongation divided by its original length. Thus:

Stress = F/A, where F is the force applied and A = cross-sectional area.

Strain = \delta/ L, where \delta is the amount of elongation and L is the original length.

Young's Modulus = stress/strain

A wire made of a material with a large value for Young's modulus will deform less than if it was made using a material with a low value of Young's modulus.