The answer is: "nothing". In fact, it's totally random. When there is a certain amount of atoms of a radioactive element, it's not possible to predict which atom will decay first and which one will decay later. We can only predict the amount of atoms that will be left after a certain time t (if we know the half-life of the element), but we can't predict which atom will decay first.
The half-life is the
amount of time in which specific atoms of a radioactive element will go through
decay. This is used as a measurement to estimate how long will it take for
one-half of the atoms in a sample to undergo radioactive decay. <span>Moreover, all
radioactive atoms undergo radioactive decay and will continue to transform into
new elements until it will reach a non-radioactive and stable isotopes.<span>
All three pendulum will attain same velocity irrespective of their mass difference in isolated system (means where air drag are negligible) and at same length
As you know when velocity is calculated we can not take mass into account.
