The Wonderful Descovery of The Physics of The Roller Coaster

THE WONDERFUL DESCOVERY OF THE PHYSICS OF THE ROLLER COASTER
Introduction
A roller coaster car moving along a pathway is a wonderful example of how energy is
transformed from kinetic energy to gravitational potential energy and vice versa. Imagine three
points on a roller coaster, each having a different height with respect to the ground. If we neglect
any sort of frictional or drag forces and focus only on the conservative forces acting on the roller
coaster car, then we can assume that the total kinetic and potential energy is conserved. That
means that energy is simply transformed from one form to another. At the highest point on the
roller coaster (assuming it has no velocity), the object has a maximum quantity of gravitational
potential energy and no kinetic energy. As the object begins moving down to the bottom, its
gravitational potential energy begins to decrease, and the kinetic energy begins to increase.
Eventually when the roller coaster car reaches the bottom, it will have a maximum quantity of
kinetic energy as all the gravitational potential energy has been transformed into kinetic energy.
“Energy” is a term that is ubiquitous in everyday conversation, but it has a specific scientific
definition. It is the ability of an object or system to do work. An example might be the kinetic
energy that a moving roller coaster car has as it speedily travels on a downhill track. That energy
can be used to do the “work” of carrying the car to the top of a subsequent hill. Similarly, the
potential energy the car possesses at the top of that hill allows it to do the work of accelerating
to a fast speed on the next downhill.
A fundamental principle of the physical world is that energy can neither be created nor
destroyed. This principle is known as “conservation of energy”. Still, energy can be transferred
between different forms, as it is in the previous roller coaster example (kinetic to potential to
kinetic). The transferring of energy to different forms occurs continuously at all points in our
world. Examples include the harnessing of thermal energy from combustion in a car engine to
the mechanical energy that allows the car to move, or the transfer of electric energy to the
mechanical rotation of a household dryer.
This lab will use the well-known paradigm of a roller coaster to illustrate conservation of energy.
A typical model of a roller coaster is to start with the cars on top of a hill that is higher than any
other hills on the track. This means that the potential energy of the cars at that point is greater
than that at the top of any other hill. In an idealized world, that potential energy is transferred
completely to kinetic energy as the cars speed down the first hill. Then, because any subsequent
hills are shorter than the first, that initial kinetic energy is more than enough required to push
the cars to the tops of those hills, as it is transferred to potential energy with the ascension of
the cars up each hill.
This idealized description implies that a roller coaster could consist of a series of equally tall hills,
and the cars would continue forever. That is obviously not the case in the real world. Intuition
tells us that cars moving along a track will eventually slow down and stop, without any additional
forces applied to them. This is due to frictional dissipation, in which the cars’ motion along the
track is converted to mechanically useless forms of energy, specifically heat and sound. Even
though this process represents a loss of energy possessed by the cars, it is not a violation of the
principle of conservation of energy. The energy simply moves from the cars to the surrounding
environment. Frictional dissipation plays a prominent role in this lab, as it does with real roller
coasters.
Objective
This lab illustrates the type of energy conversions that are experienced on a roller coaster, and
as a method of enhancing the students understanding of that concept, they will create their own
roller coasters to test out their ideas, the process of create the roller coaster will give you a small
glimpse of how engineering work in real work.
Materials
 2 Foam Pipe Insulation Tubes (about 6’ X 7/8’ i.d. x 3/8’ wall) cut in half (see instructions)
 which can be found at hardware stores:
 Masking Tape
 Marbles
 Large Wide Space- With available space to tape to.
 Metric Ruler/Measuring Tape
 Notebook
 Timer (cellphone)
Methodology
Cut pieces of foam insulation along the sides using scissors. (There may be already some already
ready). Cut the foam insulation evenly in half. To minimize the amount of energy loss due to
friction in this lab, it is necessary to construct hills that are taut rather than floppy. This is very
important to the successful execution of this lab. Taut hills can be made by applying a continuous
upward “pull” on the top of each hill. Similarly, the initial downward ramp can avoid “floppiness”
by taping the first part of it flush against the wall. You will see if is to much floppy if your ball
drops or start to bouncing or loose velocity. Taping the structure at multiple points to the floor
or objects such as chair legs is very helpful. The roller coaster course can be structurally
maintained by taping the hills and loops to other objects in the classroom, such as chairs and
tables. This will help with accurate height measurements for these obstacles.
Try to measure the union points of your roller coaster and make a diagram to help you to track
the changes that you made, this is one important part of an engineer in the design process,
having a record of his attempts.
Experiment 1. Simple roller coaster
You will have 4 or 5 pieces of foam insulation.

To start, tape 3 or 4 pieces of the foam
insulation together.
Tape the beginning of the rollercoaster at a

desired higher above the floor.
Tape the slide down some distance away

from the edge of the wall. (see figure 1)
Have one partner form a hill, with its peak
located away horizontally from the starting
point as shown in Figure 2. Do this by pulling
up on the insulation to form the peak of the
hill. It is helpful to tape the peak of the hill to a
chair leg to hold it steady. As one partner holds
it still, have the other partner drop the marble
from the start.
If the marble makes it over the hill, then raise

the height and retry. If it does not roll over, lower the hill and retry. Repeat this process until
the maximum hill height is determined (i.e. the marble nearly stops at the top of the hill.) Record
it your notebook and add some tape and make the experiment and change the high where the
ball is release.
Experiment 2: Loop roller coaster
Using the same maximum hill height

as when you dropped the marble,
stretch the hill out further from the
wall (so the center of the hill is some
centimeters from the wall). This
should result in a more gradual slope
of the hill up to the same height as in
the previous test.
If the marble makes it over the hill, then raise the height and retry. If it does not roll over, lower
the hill and retry. Repeat this process until the maximum hill height is determined (i.e. the
marble nearly stops at the top of the hill.) Now, tape down the insulation away from the starting
point as shown in the Figure 3. keep the hill height the same as the maximum height determined
in the previous step
If the marble makes it over the hill, then

raise the height and retry. If it does not
roll over, lower the hill and retry. Repeat
this process until the maximum hill height
is determined (i.e. the marble nearly stops
at the top of the hill.)
Now, make a loop which, at its tallest

point, is the same height as the value
recorded directly above. Have a partner hold it in place. See Figure 4
Drop the marble and observe if it completes the loop.

Experiment 3: Build your own roller coaster
Now, you will have a custom roller coaster! As you know, the most fun roller coasters are those
that send the riders over the highest hills. Make the most number of hills with the highest
combined height (add up all the heights - hills need to touch the ground in between), Try to
deliver the ball in a cup at the end of the ride, as it will make a safe roller coaster, and make fly
your imagination, with colors, or lights or things that you would like to propose to get better
your roller coaster.
Results and conclusions
Make a record of all your experiences and all your proposals to your roller coaster and make a
brief design in your notebook.
List of awards and honors (Medals) Commented [mc1]: Poner nombres chistosos o
representativos como curvy, or fancy, etc..
1. More time holding in on the roller coaster (
2. More loops
3. More curves
4. That gently drops in a can at the end
5. The most imaginative design

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THE WONDERFUL DESCOVERY OF THE PHYSICS OF THE ROLLER COASTER

Experiment 1. Simple roller coaster

You will have 4 or 5 pieces of foam insulation.

Tape the beginning of the rollercoaster at a

Tape the slide down some distance away

If the marble makes it over the hill, then raise

Experiment 2: Loop roller coaster

Using the same maximum hill height

If the marble makes it over the hill, then

Now, make a loop which, at its tallest

Drop the marble and observe if it completes the loop.

Results and conclusions

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