Where can I find information for a science project on Wheels in
Motion, specifically on do wheels reduce friction?

Hello.

Yes, wheels do reduce friction. Here are some explanations:

"Wheels reduce friction in two ways.  The first way is because a very
small part of the wheel actually touches the ground.  The smaller any
part is that touches the ground, the lower the amount of friction. 
This is because there is less space to actually rub together.  The
second way friction is reduced is because the wheel rolls.  The wheel
constantly has a different part of it touching the ground.  This
change allows the wheel to roll over the ground very smoothly."
source: Activity: book based Physics / Friction, hosted by
juniata.edu:
http://services.juniata.edu/ScienceInMotion/elementary/labs/friction.doc

"When you use a wheel, things do not have to slide and the work is
easier."
Source: Michigan Core Curriculum: Lesson 4 - Wheels and Pulleys
http://www.michigan.gov/scope/0,1607,7-155-13481_13482_13485-41999--,00.html

"Wheels are a common way to reduce friction. Pulling a wagon over a
concrete sidewalk is easier than pulling a slide over it."
source: FIFTH GRADE SCIENCE, hosted by utm.edu
http://www.utm.edu/departments/ed/cece/fifth/5A2.shtml

"The resistive force of friction is one of the first thing ancient
people wanted   to overcome. In order to construct buildings they had
to drag large blocks from one place to another. Friction made the job
difficult. One way to reduce friction is to lubricate the sliding
surface with oil. But this was not practical in most situations. Then
someone came up with the idea of placing logs or rollers under the
object, so that the friction was greatly reduced.
Using rollers
They used a lever to lift the object onto the rollers, and then used
the rollers to reduce friction and easily move the heavy object from
one place to another. After hundreds of years, rollers were  replaced
by the invention of the wheel on an axle. A wheel is simply a
refinement of the roller."
source: Simple Machines, hosted by school-for-champions.com
http://www.school-for-champions.com/science/machines.htm

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Here are some ideas on experiments that will help you show how wheels
reduce friction:

"Can wheels cut down on friction?" hosted by teachervision.com
http://www.teachervision.com/tv/curriculum/weeklywebadventures/extreme_sports/s_classproj.html

"OVERCOMING FRICTION 1"
"What happens to friction when we use wheels to roll an object instead
of sliding it?", hosted by galaxy.net
http://www.galaxy.net/%7Ek12/machines/fr_over1.shtml

"Learning Experience: Wacky Wheels", hosted by rice.edu
http://schoolscience.rice.edu/science/curricula/PrintPreviewLearningExperienceOnly.cfm?LEID=501&CurriculaID=140

You might also be interested in a kit from einsteins-emporium that
includes "8 to 12 different experiments" that will help you
demonstrate how wheels work.
http://www.einsteins-emporium.com/science/k-machines/sk250.htm


search strategy:
"wheels reduce", friction
"wheel reduces", friction
"wheels work", friction
wheels, experiments, friction

I hope this helps. Best of luck with your project!

The comment from the Michigan core curriculum is wrong in essence:

"When you use a wheel, things do not have to slide and the work is
easier."
Source: Michigan Core Curriculum: Lesson 4 - Wheels and Pulleys 

First of all, essentially all practical implementations of wheels DO
involve sliding.  Rollers don't involve sliding, but wheels do,
generally at some axle.  The deep and fundamental point is that the
sliding is transfered from a very large area of often soft and
unlubricated material to a very small area of very hard material that
is generally lubricated.  This means that the amount of friction is
reduced.

Consider for the moment a 10 cm thick wheel with a diameter of a meter
pierced by an axle with no bearing with diameter of 1cm.  If four of
these wheels support a piece of stone with an area of 2 square meters,
we have a decrease in the bearing area of 20,000 / 40 = 500 to 1. 
This doesn't decrease the friction in the ideal case because the
normal force goes up as the area decreases, but note that there is
also a 100:1 lever involved between the outer edge of the wheel and
outer edge of the axle.  Also, the surface of the axle is likely to be
much smoother than the surface over which we would be dragging the
stone (if only because it would polish down pretty quickly!).

Now, if we use a roller bearing around the axle, we get another boost
because the rollers transmit the force without applying any
significant force to THEIR axle.  The result is that although there is
still sliding going on, the place of the sliding, the forces involved
and the materials involved are manipulated to reduce (but not
eliminate) sliding losses.

This comment is also very misleading:

"Wheels reduce friction in two ways.  The first way is because a very
small part of the wheel actually touches the ground.  The smaller any
part is that touches the ground, the lower the amount of friction. 
This is because there is less space to actually rub together.  The
second way friction is reduced is because the wheel rolls.  The wheel
constantly has a different part of it touching the ground.  This
change allows the wheel to roll over the ground very smoothly."
source: Activity: book based Physics / Friction, hosted by
juniata.edu:

The comment about friction being lower if the area is lower is just
plain incorrect.  While the process is non-linear, dynamic friction is
generally proportional to the normal force (if area is kept constant)
and proportional to area (if the pressure is constant).  The result is
that simply decreasing area does not decrease friction.  The real
reason that a wheel on an axle without a roller bearing decreases
friction is that the point that slides is displaced to where a lever
is available to overcome the frictional force and because the axle and
wheel are generally smoother than the load and the surface the load
would be dragged on.

The part about having different parts of the wheel on the ground is so
silly as not to require any comment.

This brings up the age-old question of why in the world are basic
science texts written sooooo poorly?

Teddunning,
Thank you for your comments. You make a good point. The Michigan core
curriculum's use of the phrase "thing do not have to slide" is indeed
oversimplified and potentially misleading.

My guess is that the idea behind that explanation was probably that
kids have a intuitive grasp of the difference between rolling and
sliding.  You're right, though. It doesn't do anyone any favors to
pretend that rolling isn't a form of sliding.

Regards,
juggler