Notes:

The Barrel Ride Simulation is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Interactive can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.

Teaching Ideas and Suggestions:

This Interactive is intended for use during the middle to later stages of a learning cycle on circular motion. The Interactive provides students with the challenge of designing a safe and thrilling barrel ride. If you are not familiar with a barrel ride at an amusement park or carnival, it can be described as follows: Riders enter a large cylindrical and upright barrel through a door in the barrel. They stand next to the barrel wall. The barrel begins to spin and once it reaches a sufficiently high speed, the floor of the barrel is removed (lowered). Riders remain stuck to the wall and the force of static friction holds them in place to prevent them from falling despite the absence of a floor. There are numerous YouTuBe videos and classic black-and-white photos that can be accessed on the internet to prepare your classes for the interactive.

The Interactive includes three modifiable variables - barrel radius, spin period, and rider mass. Users modify the variables and observe the effect upon the rider. A safety and thrill report are provided; each ranks the ride on a continuum. Modifications can quickly be made until the ride meets standards of safety and thrill. Other representations included in the simulation are velocity and acceleration vectors drawn on the animated rider as it traverses the circular path, free-body diagrams, and digital meters displaying the speed, acceleration, and the number of Gs. Finally, six photos of Colonel John Stapp (of rocket sled fame) and a set of skull nones are used as displays of the level of thrill and pain.

Values for the number of Gs are calculated as the ratio of the normal force to the gravity force. Since the normal force is the only inward force and thus the net force (m•a), the ratio of normal force to gravity force is equivalent to the ratio of m•a/(m•g) or simply a/g. The upward force is the force of static friction between the rider and the barrel wall. For very small accelerations and thus normal force values, the available friction may not be sufficient to balance the force of gravity. This represents the first safety concern, causing the risk of riders falling once the floor of the ride is lowered.

The second safety concern pertains to the possibly large normal forces experienced by riders. Of course, one would want a sizeable normal force to insure sufficient friction and prevent the falling risk. But too high of a normal force can cause a rider to black out (and worse). We used the following assumptions regarding the number of Gs, the thrill rating, and the safety impact are as follows:

Thril Rating # of Gs Description Safety Impact
1 (lowest) < 1.5 For those who like rocking chairs Marginal
2 1.5 -3.0 A Kiddie Ride Safe
3 3.0 - 4.0 Definitely worth the ticket Safe
4 4.0 - 5.5 For Thrill Seekers Safe
5 5.5 - 7.0 For Dare-devils Marginal
6 7.0 - 9.0 For Skeletons Not Safe
7 (highest) > 9.0 Close the Ride! Not Safe

Our safety rating utilizes a color scale with red, orange, and yellow being the most dangerous and green being safest.  The following criteria are used to generate the color rank. A ranking of yellow can still be considered safe but is approaching the margin of danger.

Color Criteria
Red a < 5.0  OR  # of Gs  > 7.0
Orange 5.0 < a < 10.0  OR  5.5 <  # of Gs < 7.0
Yellow 10.0 < a < 15.0  OR  5.0 <  # of Gs < 5.5
Green 15.0 < a < 20.0  OR  4.0 <  # of Gs < 5.0
Green (safest)  a > 20.0  AND  # of Gs < 4.0

A free-body diagram is displayed for each trial. We did not scale the force vectors on the diagram. There is such a large range of force values that scaling them in the available space would have caused many forces to be significantly small and would not play well for those users who rely on phones to navigate our site. Instead, we have provided numerical values for each of the three forces below the diagram. Similarly, the velocity and acceleration vectors were not scaled from trial to trial. They display as the same length in every trial. Speed and acceleration values can be viewed as a digital display in the space to the right of the animation. We did provided some scaling to the circular barrel that is being designed.

The provided exercise that accompanies this Interactive guides students towards an understanding of the variables that affect the thrill and safety of a barrel ride. It is relatively open-ended while providing a framework for the investigation.

Related Resources

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Barrel Ride Simulation. These include:
• Minds On Physics Internet Modules:
The Minds On Physics Internet Modules include a collection of interactive questioning modules that help learners assess their understanding of physics concepts and solidify those understandings by answering questions that require higher-order thinking. Assignments CG1, CG2, CG3, CG4 and CG5 of the Circular Motion and Gravitation module provide great complements to this Interactive. They are best used in the middle to later stages of the learning cycle. Visit the Minds On Physics Internet Modules.

• Curriculum/Practice: Several Concept Development worksheets at the Curriculum Corner will be very useful in assisting students in cultivating their understanding, most notably ...

Speed and Velocity
Acceleration and Circular Motion
Circular Motion and Inertia
The Centripetal Force Requirement
Mathematics of Circular Motion

Visit the Curriculum Corner.

• Labwork:
Simulations should always support (never supplant) hands-on learning. The Laboratory section of The Physics Classroom website includes several hands-on ideas that complement this Interactive. Two notable lab ideas include ...

Making the Turn Lab
Loop-the-Loop Lab

Visit The Laboratory.

Additional resources and ideas for incorporating Barrel Ride Simulation into an instructional unit on circular motion can be found at the Teacher Toolkits section of The Physics Classroom website.  Visit Teacher Toolkits.