# Factors affecting the stretching of springs and rubber bands

Essay by sarahkazimHigh School, 10th grade July 2004

Aim:

To investigate the factors affecting the stretching of springs and rubber bands

Scientific Knowledge:

Before doing the experiment I came to the conclusion that this experiment relates to Hooke's Law which states that extension is proportional to the load, meaning that if you stretch something with a steadily increasing force, then the length will increase steadily too. By looking at various sources I have also found out that if a mass m on a spring is displaced from the equilibrium position (x0 = 0) to a new position x, Hooke's law states that the spring will exert a restoring force on the mass Fr = -kx. The "-" sign indicates that the direction of the spring force is in the direction opposite to the direction of the displacement. The value "k" is a constant for a given spring, but different springs have different "k-values." Thus, the force exerted by a spring is variable, specifically the greater distance it is stretched from equilibrium; the greater is the spring force attempting to restore the spring to its equilibrium position.

This relationship holds up to a point called the elastic limit. Each spring has its own value of this limit. If you stretch a spring beyond its limit, then the spring will not return to its original shape, but will remain stretched out.

Not all "springy" things obey Hooke's Law. When a rubber band is stretched, the rubber will exert a restoring force. The amount of this force depends on the amount that the rubber is stretched, but perhaps not in the same simple way as the spring.

The F=k*x expression used to calculate the spring constant leads to other uses of the spring constant. Once k is known, we can use the displacement of the spring to determine the force...