At what point on a roller coaster would a inertia forces lifting you up out of your seat be the strongest

If gases like carbon dioxide and methane make up less than 1% of the total atmosphere, why is it important for scientists to monitor changes in percentages of these gases?

Amoving electron has kinetic energy k1. after a net amount of work w has been done on it, the electron is moving one-quarter as fast in the opposite direction. (a) find w in terms of k1. (b) does your answer depend on the final direction of the electron's motion?

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.