The menstrual cycle is from Day 1 of bleeding to Day 1 of the next time of bleeding. Although the average cycle is 28 days, it is normal to have a cycle that is shorter or longer. Girls usually start having menstrual periods between the ages of 11 and 14.
In nuclear physics, nuclear fusion is a nuclear reaction in which two or more atomic nuclei come very close and then collide at a very high speed and join to form a new nucleus. During this process, matter is not conserved because some of the matter of the fusing nuclei is converted to photons (energy).
A star can NEVER exhaust its supply of hydrogen. What CAN happen is that when hydrogen is fused into helium, after a while there may be so much helium that it interferes wit â¦ h the hydrogen fusion reaction, and the star begins to fade and shrink.