Mass (say) 1 kilogram. Then we can measure the mass of any other object in the universe by colliding it with the reference object and measuring the accelerations. Additionally, mass relates a body's momentum p to its linear velocity v: and the body's kinetic energy "K" to its velocity: The primary difficulty with Mach's definition of mass is that it fails to take into account the potential energy (or binding energy) needed to bring two masses sufficiently close to one another to perform the measurement of mass. This is most vividly demonstrated by comparing the mass of the proton in the
Division by zero cookie in half. The problem with 5 cookies and 0 people cannot be solved in any way that preserves the meaning of "divides". Another way of looking at division by zero is that division can always be checked using multiplication. Considering the example above, setting "x" = , if "x" equals ten divided by zero, then "x" times zero equals ten, but there is no "x" that, when multiplied by zero, gives ten (or any number other than zero). If instead of "x" = we have "x" = , then every "x" satisfies the question 'what number "x", multiplied by