Difference Between Spring Constant and Stiffness Factor

Spring Constant vs Stiffness Factor

Spring constant and stiffness factor are two very important quantities when studying the field of elasticity. These quantities play a vital role in almost all the calculations in this field. In this article, we are going to discuss what spring constant and stiffness factor are, their definitions, applications of stiffness factor and spring constant, similarities and finally the difference between the stiffness factor and spring constant.

Spring Constant

Elasticity is a very useful property of matter. It is the ability of the materials to return to their original shape after the external forces are removed. It is observed that the force required to keep an elastic spring stretched is proportional to the stretched length of the spring. The proportionality constant is known as the spring constant and is denoted using k. This gives us the equation F = -kx. The minus sign stands for the reverse direction of x to the force. The spring constant is defined as the force required for stretching the spring by unit length. The units of the spring constant are Newton per meter. The spring constant is a property of the object. The elastic potential energy of the system is the amount of work that is required to stretch the elastic object by a given length x. Since the force applied F(x) = kx, the work done is equal to the integration of F(x) from zero to x, with respect to dx; that is equal to kx²/2. Therefore, the potential energy is kx²/2. It must be noted that the potential energy of any object attached to the end of the rod does not depend on the mass of the object but only on the spring constant and the stretched length.

Stiffness Factor (Young’s modulus)

Young’s modulus is a very important property of matter and is used to characterize the stiffness of the material. Young’s modulus is the ratio of the pressure on the object (stress) to the strain of the object. Since strain is dimensionless, the units of Young’s modulus are equal to the units of pressure, which is Newton per square meter. For some materials, the Young’s modulus is constant over some range of stress. These materials obey the Hooke’s law and are said to be linear materials. Materials, which do not have a constant Young’s modulus, are known as non-linear materials. It must be clearly understood that Young’s modulus is a property of the material, not the object. Different objects made using the same material will have the same Young’s modulus. The Young’s modulus is named after the physicist Thomas Young. Young’s modulus also can be defined as the pressure required having a unit strain on the material. Even though the units of Young’s modulus are Pascal it is not widely used. Large units such as Mega Pascal or Gigapascal are the useful units.