Homie I don’t know either♀️Drop out of schl ig ;-;
First we gotta use an equation of motion:

Our vertical distance d= 100 m, initial vertical speed u = 0 m/s (because velocity is fully horizontal), and vertical acceleration a = 9.8 m/s2 because of gravity. Let's plug it all in!

Now we just need to solve for t:

Hit the calculators, and you'll get 4.5 seconds!
The answer to the question would be jet streams.
Answer:
125÷2= 62.5 is your average speed. If the train was resting it's not moving your going nowhere . If the train is traveling at constant speed in a straight line it's speed will increase going through mountains will slow it down. if the train is coming to a braking force its speed will decrease