Closed system. If the system is not closed, matter or energy can escape from the system. an example of this is if you react magnesium and hydrochloric acid in a open system. The H₂ gas is going to escape making it look like some of the mass disappeared . in that same reaction some in an open system will also loose heat to the surrounding which will make it look like less heat was produced.
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The correct answers is 1/57
Momentum and Kinetic Energy...They both are directly proportional to the
Mass and Velocity of the object and they are the only factors which
determine them.
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