Download energy guided reading part 2

Name: ___________________________________ Period:____________
4.2 Energy and the Conservation of Energy Part 2 (pg. 88-90)
Energy
converts from
potential to
kinetic
What happens when you throw a ball straight up in
the air? The ball _________ your hand with
___________ energy it gains when your hand
accelerates it from ________. As the ball goes
__________, it gains potential __________.
However, the ball ________ down as it rises, so its
kinetic energy ____________. The increase in
potential energy is exactly _________ to the
_______________ in kinetic energy. The kinetic
energy __________ into potential energy, and the
ball’s total energy stays the ________.
Law of
conservation of
energy
The idea that __________ converts from one form into ____________ without
a change in the total amount is called the Law of Conservation of Energy.
The law states that energy can __________ be created or ___________, just
converted from one ________ into another. The law of __________________
of energy is one of the most ____________ laws in physics. It applies to not
only kinetic and _____________ energy, but to all forms of energy.
Energy can never be ____________ or destroyed, just converted
from one form into _____________.
Using energy
conservation
Energy
converts from
kinetic to
potential
The law of conservation of energy ___________ how a ball’s launch speed
affects its motion. As the ball in figure 4.14 moves upward, it slows _______
and loses ________ energy. Eventually it reaches a _________ where all the
kinetic energy has been converted to ____________ energy. At that point, the
ball is as ________ as it will go, and its upward speed has been reduced to
_________. If the ball had been launched with a ___________ speed, it would
have started with ________ kinetic energy. It would have gone ___________
before all of its kinetic energy was _____________ into potential energy. If
the exact launch speed is _____________, the law of conservation of energy
can be used to ____________ the height the ball reaches.
The ball’s conversion of energy on the way ___________ is opposite what it
was on the way up. As the ball falls, its __________ increases and its height
_______________. The potential energy decreases as it _______________
into kinetic energy. If gravity is the only __________ acting on the ball, it
____________ to your hand with exactly the same speed and ______________
energy it started with, except that it returns to your __________ from the
opposite direction.
Name: ______________________________________ Period: _____________
How to use
energy
conservation
“Conserving”
energy
Energy conservation is a __________ way to find out what happens before and
_________ a change (Figure 4.15) from one form of ___________ into
another. The law of energy ________________ says the total energy before
the _____________ equals the total energy after it. In many cases—with
falling objects, for instance—you need not worry about the force or
___________________. Applying energy conservation ______________ you
to find speeds and heights
very quickly.
Almost everyone has __________ that it is good to “conserve energy” and not
waste it. This is good ___________ because energy costs money and uses
_________________. But what does it mean to “use energy” in the
____________ sense? If energy can ___________ be created or destroyed,
how can it be “used up”?
“Using” energy When you “use” energy by turning on a ___________, you are really
converting energy from one form (_______________) to other forms (light and
__________). What gets “used up” is the ___________ of energy in the form
of electricity. Electricity is a _______________ form of energy because it is
__________ to move over long distances. In the “physics” sense, the energy is
not “________ _____,” but converted into other forms of energy. The
__________ amount of energy stays _______________.
Power Plants
Electric ____________ plants don’t make electrical energy. Energy cannot be
____________. What power plants do is convert other __________ of energy
(chemical, solar, or nuclear) into electrical energy. When someone advises
you to turn off the lights to ______________ energy, they are asking you to
use ___________ electrical energy. If people used less _______________
energy, power plants would burn less ______, gas, or other fuels in
“producing” the electrical energy they _________.
“Running out” Many people are _________________ about “running out” of energy. What
of energy
they ________ about is running out of certain forms of energy that are
_______ to use, such as oil and gas. When you use _____ in a car, the
chemical energy in the _____________ mostly becomes _________ energy. It
is impractical to put the ________ back into the form of gasoline, so we say
the energy has been “_________ _____” even though the energy itself is still
there, only in a __________________ form.