Why is it hard to drive a vertical circle ride at constant speed?

[gunblaze]

Hi ppl.. I need help on a question.

An amusement park ride (pls go to this website:--> http://www.ultimaterollercoaster.com/news/stories/img/cliff_fallstar_mar05.jpg for the pic) moves in a vertical circle. Using energy considerations, suggest why it is difficult to drive such a fairground ride at constant speed.

Any help will be strongly appreciated.

 

[Hootenanny]

HINT: Think conservation of energy, gravitational potential to kinetic and visa versa

 

[gunblaze]

thanks hootenanny.

Let me give it a try. Is it because when the ride is at the top, potential energy is at its max while at the bottom Kinetic energy is at its max. Hence, when ride is at the top, most KE has converted to PE, hence, KE is small and velocity is thus small. When ride is at the bottom, most PE has been converted to KE, Hence KE is large and thus velocity is large too.

 

[Hootenanny]

Let me give it a try. Is it because when the ride is at the top, potential energy is at its max while at the bottom Kinetic energy is at its max. Hence, when ride is at the top, most KE has converted to PE, hence, KE is small and velocity is thus small. When ride is at the bottom, most PE has been converted to KE, Hence KE is large and thus velocity is large too.

That is correct , so this means that to maintain a constant velocity the motor would have to supply a variable amount of power and there would also have to be some kind of variable breaking mechanism to prevent the ride increasing in velocity on the down stroke. The motor would have to supply energy equal to the gain in potential on the up stroke and the breaking mechanism would have to dissapate an equal amount of energy on the down stroke.