document.write( "Question 1198185: Two billiard balls collide. Ball 1 moves with a velocity of 4 m/s, and ball 2 is at rest. After the collision, ball 1 comes to a complete stop. What is the velocity of ball 2 after the collision? Is this collision elastic or inelastic? The mass of each ball is 0.16 kg. \n" ); document.write( "

Algebra.Com's Answer #831738 by ikleyn(52835) $\"\"$ $\"About$

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\n" ); document.write( "Two billiard balls collide. Ball 1 moves with a velocity of 4 m/s, and ball 2 is at rest.
\n" ); document.write( "After the collision, ball 1 comes to a complete stop. What is the velocity of ball 2 after the collision?
\n" ); document.write( "Is this collision elastic or inelastic? The mass of each ball is 0.16 kg.
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\n" ); document.write( "\n" ); document.write( "The logic and explanations in the post by @math_tutor2020 are not perfectly correct,
\n" ); document.write( "so I came to explain everything in a right way.\r
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\n" ); document.write( "\n" ); document.write( "In particular, tutor @math_tutor2020 writes quoting\r
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document.write( "    \"An inelastic collision is one in which objects stick together after impact, \r\n" );
document.write( "     and kinetic energy is not conserved.\"\r\n" );
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\n" ); document.write( "\n" ); document.write( "And then @math_tutor2020 makes a conclusion\r
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document.write( "    We can see that since the billiard balls don't stick together, \r\n" );
document.write( "    and instead separate, this means the collision is elastic.\r\n" );
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\n" ); document.write( "\n" ); document.write( "        It is NOT CORRECT. By the definition, a collision of two bodies is called inelastic collision \r
\n" ); document.write( "\n" ); document.write( "        if two bodies remain separate, but kinetic energy is not conserved.\r
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\n" ); document.write( "\n" ); document.write( "The \"sticking together\" condition determines OTHER type of collision, called
\n" ); document.write( "\"plastic collision\", or, in other terminology, \"perfectly plastic collision\"\r
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\n" ); document.write( "\n" ); document.write( "But \"inelastic collision\" means loosing of kinetic energy, only: it is transformed
\n" ); document.write( "into other types of energy (heat energy or interior energy).\r
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\n" ); document.write( "\n" ); document.write( "            The solution to the given problem is as follows:\r
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document.write( "Two bals have the same mass of 0.16 kg.\r\n" );
document.write( "Before collision, ball 1 moves with a velocity of 4 m/s; ball 2 is at rest.\r\n" );
document.write( "After collision, ball 1 comes to a complete stop.\r\n" );
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document.write( "To determine the speed of the second ball, use the momentum conservation law,\r\n" );
document.write( "which is held at any collision (elastic, inelastic, plastic).\r\n" );
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document.write( "it says  \"momentum before the collision = momentum after the collision\",  or,  for given conditions, \r\n" );
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document.write( "     = ,  or    = ,  which implies   = 4 m/s.\r\n" );
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document.write( "So, the balls \"exchanged\" their velocities after the collision.\r\n" );
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document.write( "It makes it obvious that the kinetic energy is conserved;  so, the collision is ELASTIC.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved, with complete explanations.\r
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\n" ); document.write( "\n" ); document.write( "This topic on collisions requires full and completely clear understanding, if a person claims to be an expert.\r
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