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  1. #46

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    Re: Terrifying Space Mountain experience

    Quote Originally Posted by Theophilus Carter View Post
    To those suggesting that heavier cars move faster through the track, I'm curious as to what the reasoning for this is.

    The velocity of a roller coaster car should be given(ideally) by:

    mgh = 1/2 m v^2, where m is the mass of, in this case, the rocket. Solving for the velocity, the mass cancels, and is dependent only on the gravitational constant g and the height of the track, h, and should be given by v = sqrt(2gh). Can someone explain what the flaw in my reasoning is?
    CMinParadise answered this well. Friction, the resistive force opposing the motion of two objects rubbing against each other, and drag forces, a velocity-dependent force opposing an object's motion due to collisions with air or liquid molecules (e.g., air resistance), are examples of what separates the physical world that we deal with on a daily basis from the idealized world that you were describing. A roller coaster experiences both types of forces (caused contact between the coaster's wheels/the track and collisions with air molecules that it pushes on as it progressing down the track, respectively). To explain a little more, the mass of the car wouldn't matter in a vacuum, where the situation is ideal and everything falls simultaneously, accelerating uniformly at app. 9.8 m/s^2 whether the object is a bowling ball or a feather. However, we know that if were to drop a bowling ball and a feather from the roof of your house, they wouldn't hit the ground at the same time--due to air resistance (drag), the bowling ball will hit the ground first. This is because the feather, with such a small mass and a large surface area, will reach terminal velocity much more quickly than a bowling ball (further explanation/diagrams: Elephant and Feather - Air Resistance). Likewise, for inclined planes (like the slope of a roller coaster), the motion of an object depends not only on its mass, but on the angle of the plane and the plane's coefficient of friction, which will affect the final parallel force that "pulls" the object down the plane.

  2. #47

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    Re: Terrifying Space Mountain experience

    Quote Originally Posted by gatheringrosebuds View Post
    CMinParadise answered this well. Friction, the resistive force opposing the motion of two objects rubbing against each other, and drag forces, a velocity-dependent force opposing an object's motion due to collisions with air or liquid molecules (e.g., air resistance), are examples of what separates the physical world that we deal with on a daily basis from the idealized world that you were describing.
    Actually, I don't think friction will enter into it, since friction also has a linear dependence on mass, the mass term cancels and the acceleration is still a function of g and the material properties.

    However, we know that if were to drop a bowling ball and a feather from the roof of your house, they wouldn't hit the ground at the same time--due to air resistance (drag), the bowling ball will hit the ground first. This is because the feather, with such a small mass and a large surface area, will reach terminal velocity much more quickly than a bowling ball (further explanation/diagrams: Elephant and Feather - Air Resistance). Likewise, for inclined planes (like the slope of a roller coaster), the motion of an object depends not only on its mass, but on the angle of the plane and the plane's coefficient of friction, which will affect the final parallel force that "pulls" the object down the plane.
    So, sure. For quadratic drag you can show(simply) that the velocity is dependent on both the square root of the mass, and has an inverse dependence on the hyperbolic tangent of the square root of twice the mass(that was a mouthful, which might say something about the usefulness of our analysis). I'm not sure what the relative values of these terms would be for a roller coaster car(it also depends on surface area, and on the fluid properties(these are certainly well known for air), but I have to think that both 1) the relative change in mass between any two rockets is small, and 2) The square root and the inverse dependencies probably make the effect very small(negligible or not perceptible) for a real system. That doesn't, of course, mean that the velocity of rockets is constant, since there is a dependence on the material properties, which oil on the tracks would change, but I am not buying that fluctuations in rocket mass is responsible for changes in velocity without something more substantial.

    Edit: Interestingly, there may be a dependence on the mass distribution, not on the mass of the rocket itself.
    Last edited by Theophilus Carter; 07-30-2013 at 10:26 PM.

  3. #48

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    Re: Terrifying Space Mountain experience

    I can't offer details on the physics of it, but rocket weight does play a significant role in the operation of that attraction. There's a significant chunk of hardware and operating procedures that revolves around that.

  4. #49

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    Re: Terrifying Space Mountain experience

    Pretty much what I said. The number of rockets (Space) or sleds (Matterhorn) can be adjusted based on necessity. And I know on Matterhorn (which I worked more than I worked Space), running capacity when it wasn't necessary could always lead to a greater potential for a back up and ride cascade, hence the decision to run with fewer sleds on the line when it wasn't necessary.

    Of course, as for Space, I worked it two or three decades ago now, so it's probable things have changed.

    Pushing a rocket through the station though and letting people go again simply to prevent a station backup and 101 wasn't something that was commonly done as I recall.

    And it rarely (if ever?) happened on Matterhorn. If you were working unload on Matterhorn, you monitored the holds, and if a hold 3 went to a hold 4 you could be in trouble. So you could take that preventative step by exiting guests and pulling an empty sled if it got close to that point. However, oft times you'd have to pull the sled off on the table fast so you'd just leave the guests in the sled. In that case, you'd wait for the station area to clear a bit and then put the sled back on. I'd offer the guests another ride if they wanted it, but by that time the station was clear so there was time for guests who didn't want to ride again to exit.

    On Space, the rocket was just pulled. In talking with some fellow former SM CMs I worked with, they don't remember forcing a sled through on another trip just to alleviate a potential station backup. It just seemed logical if you were in danger of going 101, you had to clear a space on the track as quickly as possible. While sending a rocket through again could certainly keep things moving better through the station, you might be sending someone on again who doesn't want to go. And by chance if you had a person who did raise their hand and say no, the ride would go down almost immediately because you'd have to let them off.

    So our priority was to monitor and yank a rocket if necessary.

    Apparently things have changed though.

    Quote Originally Posted by Infernoman View Post
    Ah! A Space thread! Time for me to chime in although looks like most of the Qs have been answered but I'll still pop in!



    They only remove rockets if there's literally NO line. Otherwise Space will always run it's usual 10+1 (+1 being the Handicap one that slides over) only other times it goes down to 9 or even 8 during an operation is say a special event where few are needed but otherwise from opening to closing 10+1 and IF they need to constant 11.

    The feeling of it being faster at night is due to the rocket being "warmer" as opposed to being "cold" since the constant moving of said rockets will keep them warmed up and thus the oil in the bearings allowing them to move easier. Another factor that wasn't mentioned is the age of the rocket. A newer Rocket will move slower because it hasn't been broken in yet and as such needs a few days to "warm up" so until then to avoid it going too slow and causing a zone intrusion, they need to make a bigger gap between it and the next rocket going in. Finally as was said earlier weight is the main factor. a heavy rocket will move faster than a light or empty rocket.

    Now if you were in any danger like say the rocket was moving too fast the computer system would have detected it and would have cause an Emergency stop. You probably were just in an older heavy rocket which caused it to move very fast. Finally if you went again, most of the time it's because we send one through the unloading part in hope of preventing a ride cascade stop (happens when all spaces in the station are occupied and there nowhere left for the next rocket to park which stops the ride) allowing the operation to continue and to many it's just a lucky group getting a chance to ride again. now if you REALLY wanted out you can tell the CM at Dispatch (and PLEASE be very vocal about it) and they'll just pull off the rocket and get you out. I worked this morning so I have no idea what happened after I left in the morning so I have no idea how no CM said a thing about you going again...Your guess is as good as mine.

    Nothing malfunctioned from what I read but sorry to hear it wasn't what you were wishing for riding Space. Hopefully next time it will be a better flight.

    ...As I see it

  5. #50

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    Re: Terrifying Space Mountain experience

    I'm curious what the details of those procedures might be, as they might prove enlightening as to what physical principle or process could be at work.

    Even allowing for air resistance to have a non-negligible effect, I think you're still looking at only a weak mass dependence. The mass distribution argument might hold more water, but I'm really not sure how much the CoM changes.

    I have to think that changes in the velocity, and therefore distribution, of rockets(or roller coaster cars generally) is due to changes in the material properties more than changes in mass or even mass distribution. I don't know of any ride procedures that depend on the mass of the rocket, rather than simply changes in the velocities of the rockets. I suppose another change could be the initial velocity of the rocket coming off the lift chains.

  6. #51

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    Re: Terrifying Space Mountain experience

    Pretty much what I said. The number of rockets (Space) or sleds (Matterhorn) can be adjusted based on necessity. And I know on Matterhorn (which I worked more than I worked Space), running capacity when it wasn't necessary could always lead to a greater potential for a back up and ride cascade, hence the decision to run with fewer sleds on the line when it wasn't necessary.

    Of course, as for Space, I worked it two or three decades ago now, so it's probable things have changed.

    Pushing a rocket through the station though and letting people go again simply to prevent a station backup and 101 wasn't something that was commonly done as I recall.

    And it rarely (if ever?) happened on Matterhorn. If you were working unload on Matterhorn, it was your job to exit the guests and monitor the holds. If a hold 3 went to a hold 4 you could be in trouble. So getting a sled off the track as quickly as possible was what you had to do. You didn't yell to the other CMs to leave everyone in their sleds and let 'em go again to clear the station.

    On Space, the rocket was just pulled, as well. And in talking with some of my fellow former SM CMs who worked the attraction at the same time I did, they don't remember forcing a sled through on another trip just to alleviate a potential station backup. If you were in danger of going 101, you had to clear a space on the track as quickly as possible. While sending a rocket through again could certainly keep things moving better through the station, you might be sending someone on again who doesn't want to go. And by chance if you had a person who did raise their hand and say no, the ride would go down almost immediately because you'd have to let them off.

    So our priority was to monitor and just yank a rocket if necessary.

    Apparently things have changed though.

    Quote Originally Posted by Infernoman View Post
    Ah! A Space thread! Time for me to chime in although looks like most of the Qs have been answered but I'll still pop in!



    They only remove rockets if there's literally NO line. Otherwise Space will always run it's usual 10+1 (+1 being the Handicap one that slides over) only other times it goes down to 9 or even 8 during an operation is say a special event where few are needed but otherwise from opening to closing 10+1 and IF they need to constant 11.

    The feeling of it being faster at night is due to the rocket being "warmer" as opposed to being "cold" since the constant moving of said rockets will keep them warmed up and thus the oil in the bearings allowing them to move easier. Another factor that wasn't mentioned is the age of the rocket. A newer Rocket will move slower because it hasn't been broken in yet and as such needs a few days to "warm up" so until then to avoid it going too slow and causing a zone intrusion, they need to make a bigger gap between it and the next rocket going in. Finally as was said earlier weight is the main factor. a heavy rocket will move faster than a light or empty rocket.

    Now if you were in any danger like say the rocket was moving too fast the computer system would have detected it and would have cause an Emergency stop. You probably were just in an older heavy rocket which caused it to move very fast. Finally if you went again, most of the time it's because we send one through the unloading part in hope of preventing a ride cascade stop (happens when all spaces in the station are occupied and there nowhere left for the next rocket to park which stops the ride) allowing the operation to continue and to many it's just a lucky group getting a chance to ride again. now if you REALLY wanted out you can tell the CM at Dispatch (and PLEASE be very vocal about it) and they'll just pull off the rocket and get you out. I worked this morning so I have no idea what happened after I left in the morning so I have no idea how no CM said a thing about you going again...Your guess is as good as mine.

    Nothing malfunctioned from what I read but sorry to hear it wasn't what you were wishing for riding Space. Hopefully next time it will be a better flight.

    ...As I see it

  7. #52

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    Re: Terrifying Space Mountain experience

    Quote Originally Posted by Theophilus Carter View Post
    I'm curious what the details of those procedures might be, as they might prove enlightening as to what physical principle or process could be at work.
    Each rocket is weighed before dispatch, and the timing of the dispatch is altered if two consecutive rockets have significant differences in mass. I.e. if the rocket is a lot heavier than the last one that was dispatched, the CM's have to delay dispatch in order give it enough room to speed up.

  8. #53

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    Re: Terrifying Space Mountain experience

    My friends went on Space Mountain the day after your experience, and the ride broke down for some weird reason.

  9. #54

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    Re: Terrifying Space Mountain experience

    The ride is way too slow. They should make it more thrilling.
    Last edited by TimmyTimmyTimmy; 07-31-2013 at 04:43 PM.
    The world according me: http://www.youtube.com/user/TimmyME

  10. #55

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    Re: Terrifying Space Mountain experience

    Quote Originally Posted by jose92397 View Post
    My friends went on Space Mountain the day after your experience, and the ride broke down for some weird reason.
    Space Mountain breaks down almost every day.

  11. #56

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    Re: Terrifying Space Mountain experience

    I have never gone straight through a second time, however I have had that experience where I feel like I'm about fly right out of my seat because it's going SO fast. But, usually, it happens towards the end of the day, which makes some sense. I hope you were okay!

  12. #57

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    Re: Terrifying Space Mountain experience

    Quote Originally Posted by Theophilus Carter View Post
    Actually, I don't think friction will enter into it, since friction also has a linear dependence on mass, the mass term cancels and the acceleration is still a function of g and the material properties.
    Never mind, you're correct on that. I worked through a quick example of objects of varying masses on frictional planes of various angles to try and visualize how these factors would effect the final acceleration (sometimes working with real numbers helps so much more than grasping at concepts), but looking back, I messed up my algebra. (I thought that subtracting the frictional force from the parallel force to find the net force would somehow create a disparity between the final accelerations, but looking back, I don't know why I thought that since both the parallel force and the normal force are dependent on the object's mass. Funny how something as simple as Newtonian mechanics can become muddled without careful and precise thought.)

    Quote Originally Posted by Theophilus Carter View Post
    Even allowing for air resistance to have a non-negligible effect, I think you're still looking at only a weak mass dependence. The mass distribution argument might hold more water, but I'm really not sure how much the CoM changes.

    I have to think that changes in the velocity, and therefore distribution, of rockets(or roller coaster cars generally) is due to changes in the material properties more than changes in mass or even mass distribution. I don't know of any ride procedures that depend on the mass of the rocket, rather than simply changes in the velocities of the rockets. I suppose another change could be the initial velocity of the rocket coming off the lift chains.
    I do see your point, though they would make a slight difference, it is hard to believe that changes in mass distribution between cars would be dramatic enough to make any noticeable change in the ride experience. I suppose it could be possible, though.

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    Re: Terrifying Space Mountain experience

    Quote Originally Posted by jose92397 View Post
    My friends went on Space Mountain the day after your experience, and the ride broke down for some weird reason.
    I was on the ride when it broke down. It was around 7:30ish when we finally got onto the ride. The ride was moving very smoothly until the end when out of no were we stoppped. The scary part of it all was we still heard other rockets going and people screaming their heads off as they went down. Luckily the other rockets eventually stopped at the straight aways. Soon they got onto the intercom and informed us there was a glitch with the breaks at the loading dock so they had to stop us and that they were going to turn on the lights so we were not sitting in the dark. Soon cast members came out to check on us. The informed us that the ride will be fixed rather quickly and were allowing us to go on the ride again. Was a very unque experience me and my siblings never experienced.


    We were also in line for splash mountain the same day when it broke down and they shut us inside the line which was different lol.

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    Re: Terrifying Space Mountain experience

    Happened to me on matterhorn. not the speed part but it was getting backed up so he asked everyone if we wanted to go again and we said yes so he sent our sleds through again. actually made my day

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    Re: Terrifying Space Mountain experience

    Well, I'm sure glad to hear that nothing critically wrong occurred! Certainly scared the pants off of me, though.

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