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When two, 1-pound, 2-inch diameter steel spheres are smashed together, enough heat is generated at the point of contact to burn a hole in a piece of paper.
This amazing demonstration visually illustrates the conversion of kinetic energy into heat energy. The kinetic energy of the two heavy moving spheres is converted into heat at the point of collision.
The size of the spheres is critical. Smaller than 2-inch metal spheres, there is not enough mass; larger than 2-inch spheres there is too much surface area on collision. No matter how hard you smash a ball peen hammer onto an anvil with a paper in between, you do not get a hole or ripples in the paper. Like in the story of Goldilocks and the Three Bears, 2-inch spheres are just right! Many believe that at the point of collision, a shock wave travels through the paper or foil. Under a microscope one can see little specks of carbon and ripples in the paper similar to the ripples in aluminum foil.
Twelve years ago, the Smashing Spheres demonstration was demonstrated to a group Teachers in Dr. Larry Peck's, AP summer program at Texas A&M, taught by Kristen Jones and Lisa McCaw. One enterprising teacher tried the demonstration later that evening with some old spheres that he had around the house. Imagine his surprise when he obtained sparks after colliding the rusty spheres together with a piece of aluminum foil held in between. He had rediscovered the thermite reaction: Fe3O4 + Al -> Fe + Al2O3 + Heat & Sparks
Since then, there has been a frantic search for rusty spheres. It is possible to rust the Educational Innovations ones, but it is usually a slow process. Dr. David Shaw, MATC in Madison, WI, has reported that a few months in the presence of fumes from the chemical storage closet works well.
Acknowledgement: In 1995, Dr. Joseph Wesney, a physics teacher at Greenwich High School showed me the smashing steel sphere demonstration. We then attempted to locate its origin. After talking sequentially with a series of physics teachers, we concluded the originator is unknown.
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Students can use the Smashing Steel Spheres in an investigation to make observations to provide evidence that energy can be transferred from place to place by sound, light, heat, and electric currents.
Students can use the Smashing Steel Spheres in an investigation to ask questions and predict outcomes about the changes in energy that occur when objects collide.
Energy is present whenever there are moving objects, sound, light, or heat. When objects collide, energy can be transferred from one object to another, typically also transferred to the surrounding air; as a result, the air gets heated and sound produced.
Students can use the Smashing Steel Spheres in an investigation to construct and interpret graphical displays of data to describe the relationships of kinetic energy to the mass of an object and to the speed of an object.
Students can use the Smashing Steel Spheres in the plan of an investigation to determine the relationships among the energy transferred, the type of matter, the mass, and the change in the average kinetic energy of the particles as measured by the temperature of the sample.
Students can use the Smashing Steel Spheres in an investigation to construct, use and present arguments to support the claim that when the motion energy of an object changes, energy is transferred to or from the object.
Students can use the Smashing Steel Spheres in an investigation that also includes a computational model to calculate the change in the energy of one component in a system when the change in energy of the other components and energy flows in and out of the systems are known.
Students can use the Smashing Steel Spheres to illustrate that energy at the macroscopic scale can be accounted for as either motions of particles or energy stored in fields.
Energy cannot be created or destroyed, but it can be transported from one place to another and transferred into or out of a system.
This demonstration visually illustrates the conversion of kinetic energy into heat energy. The kinetic energy of the two heavy moving spheres is converted into heat energy at the point of collision. When two 1-pound, 2-inch diameter, chrome steel spheres are smashed together, enough heat is generated at the point of contact to burn a hole in a piece of ordinary paper! Although there are no flames, a charred hole appears along with the odor of burnt paper. (Let the younger kids smell the burnt paper) Repeat with a piece of aluminum foil instead of the paper. A number of concentric rings are observed in the foil.
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