CONSERVATION OF ENERGY
Unit Overview
The focus of this unit is
on the law of conservation of energy and its applications in simple mechanics
problems. You will revisit the concepts of potential and kinetic energy as you solve
problems relating to the conservation of energy.
Law of Conservation of Energy
The law of conservation of energy
states that the total energy in a closed system stays the same. New energy is
not created, nor is energy destroyed, but it can transform from one form of
energy to another. In the problems for this unit, you will use the formula KE(initial) + PE(initial) =
KE(final) + PE(final). In other words, the sum of the
initial amounts of kinetic energy and potential energy in an isolated system is
equal to the sum of the final amounts of kinetic energy and potential energy in
that system.
Recall from the previous
unit that kinetic energy (KE) = 1/2mv2 and potential energy (PE) = mgh. Both of these equations result in units of Joules (J).
You will encounter problems where you need to use these equations, both on
their own and in a larger context, in order to show the conservation of energy.
Read the following
information to further explore the concept of the conservation of energy:
Potential Energy – Applications
The type of potential
energy known as gravitational potential energy is what we will focus on in this
unit, similarly to the last unit. Recall that this is the energy of position.
So what factors are involved? The object in question’s mass, height above a
given surface, and the force of gravity are used to calculate that object’s
gravitational potential energy. Read through the following lesson on
gravitational potential energy:
Kinetic Energy – Applications
You may remember from the
previous unit that kinetic energy is the energy of motion. So because an object
is moving, its kinetic energy can be measured. Kinetic energy can be calculated
if you know the object’s mass and its velocity. Learn more from the following
lesson on kinetic energy:
Practice Problems
Complete the practice
problems at the following website and check your answers to see how you did.
http://www.physicsclassroom.com/class/energy/Lesson-2/Application-and-Practice-Questions