spectral lines or signatures of elements depend on temperature, the temperature of the sun is about 5800 K.
at this temperature most calcium atoms are excited to higher energy states than hydrogen atoms and this means that calcium atoms are gonna have more signatures than the atoms of hydrogen.
the statement that the sun shows weak hyrogen lines and strong calcium line is wrong because at the sun's temperature most of the hydrogen atoms are in lower energy states while calcium atoms are in higher energy states hence calcium has more or ''strong'' lines than hydrogen.
2 someone's glasses could fall of because of the inertia roller coaster is in motion but your glasses are opposing and resisting that motion due to inertia....
1 there is a possibility that electrons move from wheels to the rail and vice versa which also means that it is producing some kind of electrical energy
