I have read that the Sun produces $2 \times 10^{38}$ Neutrinos per second weighing in at approximately 8 MeV. I have 2 questions. Is there any way to calculate how many neutrinos have been produced in the past 13.5B years? Is this mass part of the calculation of the "visible" mass of the univer...

According to the textbook, the ball will nearly climb the same height (a little less but never greater), why? I came across a question in SS Krotov where it was asked why does the ball not climb the same height in the double inclined plane when it goes from one end to the other.

When we want to remove a cork from a bottle first we turn the cork. Turning in one direction makes it easier to remove in the axial direction. Does anyone know something more on this?