# Roller coaster help

#### shimmeringlight

i know and think that the when the mass inreases, the speed of the coaster does not change... this is according to researching on some sites simulators... it hinkt thats right...

and because the speed esont change, the time doesnt change?

but when i think about it more, im nto sure because i cannot prove it with the conservation of energy equation... or at least i dont think im right, cuz if the i put it into the equation where you have the Ek=1/2mv^2, then when mass gets larger, then the energy will get larger...

i dont know what im talking about, im very confused.

#### primarygun

i know and think that the when the mass inreases, the speed of the coaster does not change
Unless there is a net force acting on it.
Normally, in a frame without any net force, the momentum of an object is conserved all the time.
momentum=mass times velocity
As you see, if the mass increase, the velocity decreases as they are inversely proportional.

#### shimmeringlight

http://www.funderstanding.com/k12/coaster/

i was looking at this site, and kind of based it on it... because when i move the mass thing it doesnt change the velocity... but i also know that you can adjust the speed.

... but in a roller coaster, if the mass increases or decreases in a roller coaster, isnt it suppose to go the same?

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