gravity is the one to blame .
gravity pulls down the biker closer to earth so it goes faster going down and slower going down
that depends. If you are Going down hill then in the air is faster.
Movement is one example - Energy can be transferred from potential Energy (PE) to Kinetic Energy (KE). The classic example of this is the biker at the top of the hill. The biker has a lot of (PE) because he is at the top of the hill and that can be transferred to (KE) as soon as he starts going down the hill. The biker is now in motion and is now in the form of (KE). When he makes it to the bottom of the hill and is at a stop, he no longer has (PE) like he did when he was at the top of the mountain.
because if you going down hill its faster because its a mountain
Going up a hill would make your acceleration decrease or cause it to be slow. Going down a hill would make acceleration increase causing you to go faster.
Somewhere around 35 - 40 mph... faster if you're going down a big hill!
push it down a hill
If you are driving a loaded tractor trailer, you would downshift to gain more power when going up hill and downshift to control speed when going down hill.
Cycle down a hill.
drive down hill
go down hill
Light
a skier going up a hill a skier going down a hill