Download 5 Forms of Energy

Physical Science
Notes
Name: ________________________________________________________
Date: _______________________
Period: _____________
Energy, Work, and Machines
What is Energy?
Everything in the universe is either composed of __________________ or _________________. Remember, we learned that matter is
anything that has _______________ and takes up __________________. For example, pizza is matter because it occupies space and has mass. But,
what is energy?
Energy is EVERYWHERE!!! It is present when lightning strikes, when water rushes over Niagara Falls, stone
rolling down a hill, star shining in space, a leaf blowing in the wind, and ice melting in a pond are all examples of energy. It is hard to
say just what energy really is, but we do know what energy does – it provides us with the ability to do work or cause change.
QUESTION: Do you think the heat from a pizza is matter? What about calories from eating a pizza? If not, then what are they? Explain.
Kinetic and Potential Energy
There are two main types of energy:
1. Kinetic Energy – the energy of ______________________; the energy being used.
FUN FACT: The word kinetic has a Greek derivation ‘kinetikos’ which means MOTION!!!
2. Potential Energy – the energy of ________________________; stored energy
Read each situation below, and circle whether it shows kinetic energy or potential energy. Hint: look for key words.
1. A flying rubber band
KINETIC
or
POTENTIAL
2. A brink held high above the ground
KINETIC
or
POTENTIAL
3. A wrecking ball demolishing a building
KINETIC
or
POTENTIAL
4. A stretched rubber band
KINETIC
or
POTENTIAL
5. A tightly stretched archer’s bow (before release)
KINETIC
or
POTENTIAL
Sample Pendulum
Position A:
Maximum potential energy and no
kinetic energy
Position B:
Maximum Kinetic energy
Position C:
Maximum potential energy and no
kinetic energy
Have you ever watched a ball bounce? If not, drop any ball and watch what happens as it bounces. First, you will notice that
the ball ________________________ lower and lower after each bounce. It also makes a ______________________ when it makes contact with the
round. A bouncing ball undergoes a number of energy changes.
The ball exhibits change between the two main types of energy: __________________ energy and ________________ energy. The potential
energy of the ball is stored energy and is determined by its position. The kinetic energy is energy in motion. As soon as the ball
begins to drop, some of the potential energy is concerted into kinetic energy. As the ball drops, more and more potential energy is
______________________________ into kinetic energy until there is only kinetic energy. (This happens at the moment the ball makes contact
with the ground.) As the ball rises back into the air again, kinetic energy is being converted in potential energy, but it is never as much
as the starting potential energy. Can you label the energy changes?
QUESTION: Why does the ball bounce lower with each bounce? What happens to the energy?
Energy is Convertible
Most activities can be traced back to solar energy. However, a number of energy conversions are needed to transform the
energy. When one form of energy is changed into another form of energy, it is called an energy conversion. In any given situation,
energy can be traced back to one of the 5 main energy sources: mechanical, heat, chemical, nuclear, and electromagnetic.
QUESTION: Can you label the following types of energy?
A pizza has an assortment of energy associated with it. When you digest a pizza, _________________________ bonds are broken and
chemical energy is __________________________. A pizza coming straight out of an oven is transferring a lot of heat or thermal energy
because the particles that make up the pizza are moving relatively fast. As the pizza cooks in the oven, you may hear a sizzle because
sound energy is being ____________________________ to your ears. As the pizza sizzles, cheese may be bubbling up and down. The motion of
the cheese can be called mechanical or kinetic energy, energy associated with the motion of _______________________. If an electric oven
cooked the pizza, then electrical energy was involved in its preparation. Perhaps __________________________ used by the oven was
produced at a nuclear power plant from nuclear energy. As you can see, many kinds of energy are involved with making pizza. And, if
we continue to explore the pizza-making process, we would find even more examples of energy.
Energy can be categorized by source, type, or form.
5 Forms of Energy
Type of Energy
Characteristics
Examples
It’s the Law!!!
No matter how many conversions energy may go through, we can never destroy energy or create more of it. The principle of
the Law of Conservation of Energy always holds true. It states: energy cannot be _______________________or _____________________, but can
only be changed from one form to another. In the process, some energy is always ________________________ or “lost: as heat energy. For
example, a television converts __________________________ energy into __________________ energy that can be seen as the picture, and
__________________________ energy that can be heard. However, not all the energy is being converted into light and sound. Some is
converted or “lost” as ______________________________ energy. If you put your hand on the back of a television, you can feel this heat.
In this situation,
electrical energy is
converted into what
three types of energy?
What is Work?

Work – force applied through a distance.

Work equation : Work (Joules) = Applied Force (Newtons) x Distance (meters)

W = Fd
Practice
1. You push a refrigerator with a horizontal force of 100N. If you move the refrigerator a distance of 5 m while you are pushing, how
much work did you do?
2. A couch is pushed with a horizontal force of 80 N and moves a distance of 5 m across the floor. How much work is done in moving
the couch?
3. The brakes on a car do 240,000 J of work in stopping the car. If the car travels a distance of 40 m while the brakes are being applied,
how large is the average force that the brakes exert on the car?
What is a Machine?


A machine is a _____________________ that makes work easier. Machines change the ______________ and/or _______________________
of the exerted force.
There are two ways to classify machines:
o Simple – a machine that does work with only one movement of the machine. There six types of simple machines.
 Lever
 Pulley
 Wheel and axle
 Inclined Plane
 Screw
 Wedge
o Compound – a combination of two or more simple machines. It combines two wedges and two levers.
 Example: A bicycle
How Are Machines Useful?



Increase speed
o Ex: Bicycle
Change direction of force
o Ex: Ax used to chop wood
Increase force
o Ex: Jack used to lift a car
Machines Increase Efficiency

Machines increase efficiency by increasing speed and force.

Efficiency – the ratio of output work to input work; often measured in percent

Efficiency equation – Efficiency (%) = Output work (Joules) x 100
Input work (Joules)

E = Wout x 100
Win
Practice
1.
You do 20 J of work in pushing a crate up a ramp. If the output work from the inclined plane is 11 J, then what is the efficiency of
the inclined plane?
2.
Find the efficiency of a machine that does 800 J of work if the input work is 2000 J.
3.
The input work on a pulley system is 75 J. If the pulley system is 84 percent efficient, then what is the output work from the pulley
system?
Mechanical Advantage

Mechanical Advantage (MA) – the number of times a _________________________ increases the effort force.

Mechanical Advantage Equation: Mechanical Advantage = Output force (Newtons)
Input force (Newtons)
MA > 1: Force is increased
MA < 1: Distance is increased
MA = 1: Only distance is changed




MA = Fout
Fin
Practice
1. A worker applies an effort force of 20 N to open a window with a resistance force of 500 N. What is the crowbar’s MA?
2. Find the effort force needed to lift a 2000 N rock using a jack with a mechanical advantage of 10.
3. A crate weighs 950 N. If you can use a pulley system to lift that crate with a force of on 250N, then what is the mechanical advantage
of the pulley system?