Download Conservation of Energy Notes

Chapter 4: Energy
Date:____________
Section 2: Conservation of Energy - Notes
Learning Goals:
 Describe how energy can be transformed from one form to another.
 Explain how the mechanical energy of a system is the sum of the kinetic and potential energy.
 Discuss the law of conservation of energy.
Energy Changing Forms:
 Energy is constantly _______________________________________.

_______________________________________ is one of the main types of
energy transformations that occur today.
o What are some examples that you have used so far today?

Fuel stores ______________________ potential energy in its chemical bonds.
o
In a car:

A spark plug fires, converting chemical energy into ____________________ energy.

The hot gas expands and moves parts of the car (______________________ energy).
Mechanical Energy:
 Mechanical energy: the total amount of ________________________ and
___________________________ energy in a system.
o

The objects on the shelf have __________________________energy.
o

ME =
The objects also have __________________________ energy.
When the objects fall, they lose _____________________ energy, but gain
_____________________ energy.
o
No energy is truly “gained” or “lost”. The energy is
________________________________.
o

The amount of mechanical energy _______________________________.
Example: A swing has a potential energy of 100 J and a kinetic energy of 55 J at a certain spot. What is
the mechanical energy of the swing?
Projectile Motion:

As a projectile is launched upwards, it has mostly ______________________ energy.
o
As the velocity decreases, kinetic energy ________________________ and GPE
_________________________.
o
As it falls, GPE ______________________ and kinetic energy
_____________________ again.
Conservation of Energy:

Law of Conservation of Energy: energy cannot be _________________
nor _______________________, only transferred or transformed.
o
The amount of energy in the universe has always been the
_______________!!

As you swing on a swing, _____________________________ and
_______________________slow the swing down.
o
This doesn’t mean that energy is “lost”, it has only been converted to ____________________
______________________.
o
Friction always converts energy into _____________________________________.
Mass to Energy:

During some processes, ____________ is converted into ________________________.

This is represented by Einstein’s famous equation ___________________.

Two examples of this are :
o
_________________________________ (like in the Sun)
o
_________________________________ (like in a nuclear power plant)
Energy Conversions:

You also obey the law of conservation of energy:
o
Your body obtains energy from the ________________ that you __________.

o
You ________________ it and break it down to get the energy out.
Your body either uses the energy immediately or stores that energy as fats and carbohydrates
in your body.
o

When you require energy, your body converts those energy stores to other forms of energy.
The ____________________________ is a unit used by nutritionists to measure how much energy you
get from various foods.
o



Every gram of fat provides 9 Cals of energy – how many J?

Every gram of carbohydrates or protein provides 4 Cals of energy – how many J?
We all depend on _________________________ every day.
o

1 Calorie (Cal) = _________________
Have you ever wondered where that electricity comes from?
________________________________ convert other types of energy into electrical energy.
o
Coal Power Plant: _______________________  Electrical
o
Oil and Natural Gas: _______________________  Electrical
o
Solar Power: _______________________  Electrical
o
Nuclear Power: _______________________  Electrical
o
Hydroelectric: _______________________  Electrical
o
Wind: _______________________  Electrical
How it all works:
o
o
Energy is needed to make a _______________________ spin.

________________________________ (wind or water)

________________________________ (steam)
The rotating turbine spins an _______________________________________________ which
produces electricity.