Transcript EMM Energy Review

Practice and study guide for the test
▪ Energy transformations-types of energy
▪ Machines- not needed for this test
▪ Motion- not needed for this test
What are the parts of a battery?
 Anode +, Cathode -, and electrolyte
How does a battery work?
 Chemical reaction allows flow of electrons
What energy is in a battery?
 Potential chemical energy
How is energy stored in a battery?
 Chemical Potential Energy
What energy transformations take place between
a battery and a light bulb? Battery and motor?
 Chemical Potential Energy Kinetic Energy
Electric Energy Light/Rotational Energy
Heat Energy
What are wet cell and dry cell batteries?
 Wet= liquid electrolyte, Dry= Paste electrolyte
How does charge time affect stored energy in a
battery?
 Longer charge = more stored energy, until
chemical reaction is totally reversed and battery
will no longer charge
Which draws more energy, the light bulb or the
motor?
 The motor draws more because in our tests, it
used the battery power quicker than the light
bulb with evenly charged batteries.
What is force:
 A push or a pull
What is elastic force?
 The resistant force exerted that wants to return
something to its original state (rubber/elastic)
What is gravitational force?
 The pull of objects toward a larger object (toward the
center of the earth)
What is frictional force?
 A force that opposes motion like sliding friction or air
friction.
Weight vs. mass?
 Weight is a measure of gravitational force (we
typically use spring scales). Weight changes
based on gravitational pull (100N on earth
would be 16.7N on the moon).
 Mass is a measure of the amount of matter in
an object (we always use a balance to find
mass). Mass does not change (100g=100g).
 Mass and weight are often the same on earth.
How does surface type affect frictional force?
 Smoother surfaces typically create less friction.
Rougher surfaces typically create more friction
between objects.
How does weight affect frictional force?
 More weight was more pressure on the surface
and a greater amount of friction was created.
Surface area does not have a large impact of
frictional force.
Which battery configuration provides the best
performance to a motor? Why?
 Series connections have the most voltage
because the voltage of each battery is added
to the total. This creates more force from the
motor, but if one connection fails, they all do.
 Parallel connections do not increase voltage
so performance is low. However, they are
reliable and work even if one cell fails.
 Hybrid connections can be the best of both.
If energy is the ability to do work, what is work
to a scientist?
 Work happens when a force (Newton) is
applied to an object and it moves a
measurable distance (meter). W=F x D.
Power is the rate at which work is done. How
do scientists calculate power?
 Scientists use the formula: Power=Work/time
 Power is known as a Watt, or 1Nm/sec.
If it takes 45 Joules and 5 seconds for Mr. Jez to
move a box, how many Watts were used?
 ???
 P=W/t P=45/5 = 9Joules/sec., or 9 Watts

Keep studying and get smart!