Starting next class, we will begin to investigate oscillatory motion.
One of the simplest oscillating systems is a mass attached to
a spring. If the mass and spring are initial at rest,
in equilibrium,
and then you displace the mass by a distance **x = 5 cm**,
you can figure out the size of the restoring force of the spring:

But what if someone displaces the mass and tells you, not the absolute size of the displacement, but only the fractional (or percentage) size of the displacement -- is there anything you can deduce from that?

YES. The study of relative changes in size or position
due to applied forces and pressures involves a quantity
called **ELASTICITY**.
You will find out later today that there is a very
close connection between

RELATIVE displacements ABSOLUTE displacements ----------------------- ------------------------- Young's modulus E force constant k strain modulus S bulk modulus B

The "modulus" properties of materials are very, very important for engineers, since they describe what will happen to an object -- such as a beam or pillar or strut -- when it is placed under some stress.

Copyright © Michael Richmond. This work is licensed under a Creative Commons License.