Roller Coaster Physics: Finding Final Velocity

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Discussion Overview

The discussion focuses on the physics involved in designing a roller coaster, specifically how to calculate the final velocity of a coaster at the bottom of a slope given gravitational acceleration, slope angle, and distance. Participants explore concepts related to energy conservation, the impact of slope and distance, and the effects of air resistance on velocity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant asks for equations to find final velocity on a slope, providing specific measurements (45 degrees, 21 feet).
  • Another participant suggests using conservation of energy principles, stating that kinetic energy (KE) and potential energy (PE) are constant, and that speed depends on height difference rather than slope angle.
  • A participant questions whether the distance on an incline affects the time taken, which could influence the final velocity.
  • There is a query about incorporating air resistance into the calculations.
  • Another participant asserts that speed is independent of time and slope angle, emphasizing that only height matters for speed, while angle affects the time to reach the bottom.
  • One participant notes that roller coaster designers account for energy losses due to rolling resistance and aerodynamic drag, mentioning that these factors can vary with temperature and that some coasters use speed adjusting devices.

Areas of Agreement / Disagreement

Participants express differing views on the relevance of slope angle and distance in determining final velocity, with some asserting that only height matters, while others suggest that time and distance may also play a role. The discussion remains unresolved regarding the impact of air resistance and how to incorporate it into the calculations.

Contextual Notes

Participants reference various assumptions, such as ignoring wind resistance and friction in initial calculations, and the complexities introduced by air friction and rolling resistance. There is also mention of the variability in resistance factors based on temperature.

cookieworks
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believe it or not, this is a totally serious question. I am currently trying to design a roller coaster. Given that it is at a slope, what equation(s) would i use to find final velocity knowing gravitational acceleration, slope, and distance of my slope? ex: my slope is 45 degrees in a downward direction at a distance of approximately 21 feet (15 feet up, 15 feet over). what equation would i use and how would i implicate all of the variables into it?

P.S. you are dealing with someone who is here because all of his teachers failed him. sorry if i spelled anything wrong.
 
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welcome to pf!

hi cookieworks! welcome to pf! :smile:
cookieworks said:
… what equation(s) would i use to find final velocity knowing gravitational acceleration, slope, and distance of my slope?

conservation of energy …

KE + PE = constant …

https://www.physicsforums.com/library.php?do=view_item&itemid=132" = constant

v2 + 2gh = constant (v is speed, is height)

the speed v depends on the difference in height, h, and not on the angle of the slope at all

(of course, this ignores things like wind resistance, friction in the bearings, etc)
 
Last edited by a moderator:
but with the distance added in there on an incline, wouldn't the time vary, changing the velocity at the bottom of the hill?
 
how would i add in resistance as well assuming that i am only dealing with air friction?
 
speed does not depend on time, or on angle of slope, only on height …

all the angle does is change the time it takes you to get there
cookieworks said:
how would i add in resistance as well assuming that i am only dealing with air friction?

do experiments with actual cars loaded with people or dummies (or find out from existing roller-coasters)
 
The roller coaster designers are aware of the energy losses in coaster (rolling resistance and aerodynamic drag). The rolling resistance factor varies with temperature, mostly due to the lubricants involved. Some coasters will use speed adjusting devices like spinning tires to correct the speed of the cars mid-track.
 

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