1
CONSERVATION LAWS IN PHYSICS
1. Up to this point we have dealt only with Newton’s laws of dynamics:
a)
Fma
(First and second laws)
b)
AB BA
FF (Third law).
2. We now turn to a discussion of the conservation laws of physics:
a) conservation of energy
b) conservation of linear momentum
c) conservation of angular momentum
3. We will use Newton’s laws to derive these important conservation theorems (or
laws). It is important to understand that we will not “prove” the conservation laws,
but simply derive them as consequences of Newton’s laws.
4. A conservation law or theorem states that a certain defined quantity remains
constant no matter what changes may occur. This quantity has the same numerical
value before and after the changes occurred. For example, forces may act on an
object between some initial and final time, or between some initial or final position,
but certain quantities have the same value in the final state as it had in the initial
state.
5. The application of these conservation laws allows us to reach certain conclusions
about the state of an object without the need for a detailed analysis of all of the
various forces acting on it in a given situation in the course of its motion. The
quantities: kinetic energy, work, potential energy, linear momentum, and angular
