<h2>Answer: protons and neutrons.
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The atomic nuclei of almost all elements consist of protons and neutrons.
The nucleus of an atom has very small dimensions. However, it <u>occupies its central part and concentrates more than 99% of its total mass.
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It is in the nucleus that the protons (positive charge) and neutrons (neutral charge) are found.
: You could make slight changes to the process or consider wheather the experiment was carried out correctly
the action and reaction do not lead equilibrium if action and reaction force react on different objects
Initially, the velocity vector is 
. At the same height, the x-value of the vector will be the same, and the y-value will be opposite (assuming no air resistance). Assuming perfect reflection off the ground, the velocity vector is the same. After 0.2 seconds at 9.8 seconds, the y-value has decreased by 
, so the velocity is 
.
Converting back to direction and magnitude, we get 
