Sorry I'm late. Also sorry you couldn't handle any of this on your own.
There's not that much to it. If you ignore friction, then the total energy
is constant.
-- At the top, it's all potential energy, and kinetic energy is zero.
-- At the bottom, potential energy is zero and it's all kinetic energy.
-- Halfway down, it's half potential energy and half kinetic energy.
The real truth is that there's always some friction, friction robs kinetic
energy whenever he's moving, so eventually he stops going up and
down. Then he has to put some muscle energy into it to go some more.
An electron in the Bohr model of hydrogen revolves around the nucleus to possess energy.
Answer: Option B
<u>Explanation:</u>
According to Rutherford, it was stated that electrons are the subatomic particles which revolve around the nucleus. But the error of spiral collapse of these electrons is due to absence of electrons in discrete levels. Hence, in Bohr atom model, the atom's negative or electrons are said to rotate in respective energy levels.
So, they keep on revolving around a nucleus in Bohr atom is said to revolve around a nucleus in order to possess energy. Thus, each level will exhibit discrete energy levels which will contain electrons of specific energy only.
I am not sure, but i believe it is the distance from the viewing.
Yes. Think of block sitting on top of a bigger block. If the bottom block moves, it will drag the top block with it. Since the force of friction on the small block and its displacement are in the same direction, the "work" is positive. The static friction is a passive force, It is not a source of energy; it transmits the force placed on the bottom block. (And the "work" done by the friction on the bottom block is exactly the negative of the work done on the top block.)