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A sphere moving on a smooth horizontal surface (the xy<\/em>-plane) impacts a set of 13 cubes at rest on the same surface. This impacts leads to a number of subsequent impacts among these cubes. The resulting motion is quite complicated; however, since there are no forces acting on the system of the sphere + cubes<\/em><\/strong> in the x<\/em>– and y<\/em>-directions, we know that linear momentum for that system is conserved in both directions.<\/p>\n The animation below shows the results of a simulation of these impacts.<\/p>\n As expected, both of the x<\/em>– and y<\/em>-components of linear momentum for the system are a constant, even through the times of impacts. It is easy to see that the individual momenta of the particles are NOT constant.<\/p>\n Another observation to make from these simulation results is that the energy in the system is NOT constant. A loss of energy occurs across each impact seen in the motion. Why is that?<\/p>\n In conclusion, conservation momentum does NOT imply conservation of energy<\/em><\/strong> (and, vice versa). This is a very important general concept to remember!<\/p>\n","protected":false},"excerpt":{"rendered":" A sphere moving on a smooth horizontal surface (the xy-plane) impacts a set of 13 cubes at rest on the same surface. This impacts leads to a number of subsequent impacts among these cubes. The resulting motion is quite complicated; however, since there are no forces acting on the system of the sphere + cubes … Continue reading Momentum conservation<\/span> ![](\"https:\/\/www.purdue.edu\/freeform\/me274\/wp-content\/uploads\/sites\/15\/2020\/05\/section_04C_02.gif\")
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