Lead has a molar mass of 207.2g mol -1. Assuming that it is composed entirely of 206Pb, 207Pb and 208Pb, and that the percentage of the two lightest isotopes are equal. Calculate the relative percentage of these isotopes in the natural element

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question: ray weighs 100 kilograms, his wrestling partner, bobby, weighs 50 kilograms. if ray moves at 4 m s , how fast will bobby have to run at him to apply an equal amount of kinetic energy?

answer: 8 m/s he needs to run twice as fast to keep up so he has some work to do

explanation:   if the mass has units of kilograms and the velocity of meters per second, the kinetic energy has units of kilograms-meters squared per second squared.

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(jacemorris04)