Physics
posted by Paul on .
I am a little confused about kinetic and potential energy regarding roller coasters. I understand that the first hill has to be the highest to gain the potential energy (PE).
I hope someone can help with this example I just made up to help me understand:
1st Hill: 50 m from ground
1st Drop: 10 m from ground
2nd Hill: 40 m from ground
2nd Drop: 1 m from ground
3rd Hill: 45 m from ground
Are my explanations correct:
1st Hill: gains the maximum potential energy (PE) and zero kinetic energy (KE)?
1st Drop: gains KE, but still has some PE since its not to 0 meters from ground?
2nd Hill: mostly PE, and a little KE?
2nd Drop: mostly, mostly KE, a little tiny PE?
3rd Hill: mostly PE, a tiny bit KE?
Does it matter that the 3rd hill is bigger than the 2nd hill? Is it the 1st hill that matters?
If there is a drop lower than the first drop (like 2nd Drop and 1st Drop above), will all the PE from the 1st Hill still go to ALL kinetic energy in the 1st drop even though its not all the way to the bottom/isn’t the lowest drop?

1st Hill: 50 m from ground
1st Drop: 10 m from ground
2nd Hill: 40 m from ground
2nd Drop: 1 m from ground
3rd Hill: 45 m from ground
Are my explanations correct:
1st Hill: gains the maximum potential energy (PE) and zero kinetic energy (KE)?
AGREE (ASSUMING IT IS STOPPED UP THERE)
1st Drop: gains KE, but still has some PE since its not to 0 meters from ground?
AGREE
2nd Hill: mostly PE, and a little KE?
AGREE
2nd Drop: mostly, mostly KE, a little tiny PE?
AGREE
3rd Hill: mostly PE, a tiny bit KE?
AGREE
Does it matter that the 3rd hill is bigger than the 2nd hill? Is it the 1st hill that matters?
YES, EXACTLY, MAXIMUM HEIGHT DETERMINES TOTAL ENERGY AVAILABLE
If there is a drop lower than the first drop (like 2nd Drop and 1st Drop above), will all the PE from the 1st Hill still go to ALL kinetic energy in the 1st drop even though its not all the way to the bottom/isn’t the lowest drop?
NO, THE PE DOES NOT GO TO ZERO UNTIL THE CAR IS AT GROUND LEVEL.
YOU ALREADY ANSWERED THAT IN YOUR ANSWER TO THE FIRST QUESTION:
1st Drop: gains KE, but still has some PE since its not to 0 meters from ground?
BY THE WAY, THE SELECTION OF ZERO POTENTIAL ENERGY LEVEL IS ARBITRARY. WE JUST TYPICALLY TAKE ZERO PE AT GROUND LEVEL. HOWEVER IT IS "DIFFERENCES' IN HEIGHT THAT COUNT FOR POTENTIALS. 
thank you so much!