Задача 31659.

From the tower a stone is thrown horizontally at a speed of 20 m / s. After how many seconds will the stone speed increase twofold? What angle with the vertical will be the velocity vector at this moment?

A detailed solution with a brief description of the condition, formulas and laws used in the solution, the derivation of the calculation formula and the answer.
If you have any questions about the solution, please write. I try to help.