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Posers and Puzzles

Posers and Puzzles

  1. 19 Feb '07 23:53
    I dont know the answer to this one and I hope that you guys can help me.

    A truck is driving on a curve which way will the truck fill over. Will it fill to the outside of the curve or to the inside.Please consider that the roads could be in different condtions including rain or snow.

    I did ask someone who is smart and he said that it could go either way but was not sure.
  2. 20 Feb '07 00:38
    Centrifugal force pushes the truck toward the outside of the curve: if it falls it will go in that direction.

    Just think about when you go around a tight bend in a car: you are pushed toward the outside of the curve.
  3. Standard member PBE6
    Bananarama
    20 Feb '07 00:49 / 1 edit
    Originally posted by bloodyboy
    I dont know the answer to this one and I hope that you guys can help me.

    A truck is driving on a curve which way will the truck fill over. Will it fill to the outside of the curve or to the inside.Please consider that the roads could be in different condtions including rain or snow.

    I did ask someone who is smart and he said that it could go either way but was not sure.
    In order to drive on the curve, the road must exert an inward force on the truck's tires (centripetal force). This force produces a rotational moment about the truck's centre of gravity. Since moments are coupled, and the tires are being pushed in, the top of the truck will get pushed out. If it tips past the point where the centre of gravity is supported by the tires, it will fall over, towards the outside of the curve.
  4. Standard member XanthosNZ
    Cancerous Bus Crash
    20 Feb '07 03:12
    Originally posted by GregM
    Centrifugal force pushes the truck toward the outside of the curve: if it falls it will go in that direction.

    Just think about when you go around a tight bend in a car: you are pushed toward the outside of the curve.
    http://en.wikipedia.org/wiki/Fictitious_force#Circular_motion

    You are confusing your frames of reference.
  5. Subscriber AThousandYoung
    It's about respect
    20 Feb '07 04:35 / 2 edits
    If the road is on a plane, the truck's inertia will tend to resist it's turning. If the truck goes fast enough and is topheavy enough or just heavy without enough traction, it will go to the outside of the curve, or technically, will go in a straight line while the road curves away from the truck.

    However, in real life curved roads are generally not planar, but rather banked to prevent exactly this sort of problem. On such a curving road, the truck could still go outside, but if it's topheavy enough or has extremely bald tires and it's raining on the greasy road and the truck's going really slow, it's conceivable it could fall inside.

    However going outside is more likely overall.
  6. 20 Feb '07 07:02
    As far as I know, there are a relatively small number of factors.

    As has been mentioned, inertia will tend to push the truck outward, since inertia favors the truck heading straight, and it will be pointed outward when on a curve.

    However, many such curves have been engineered to allow the trucks (and other vehicles) to resist this pull, by making the outside higher up. Thus inertia results in greater frictive contact with the surface, which allows the vehicle to better follow the road. It also causes gravity to factor into the equation, because gravity will try to pull the vehicle down the slope towards the center.

    How well this works is dependent on the angle chosen, the conditions of the road, the sharpness of the turn, and how fast the vehicle is traveling. A slow car trying to navigate a wide curve with a steep inward pitch will be pulled inward, while a fast vehicle trying to navigate a nearly flat and sharp curve will be hard pressed to keep from going off the outside edge.
  7. Standard member Briscoe
    Consigliere
    20 Feb '07 18:11
    sure...you can use physics...

    ...OR...

    ...common sense says you can just look at what side the guard rails are on
  8. 20 Feb '07 18:33
    Originally posted by bloodyboy
    I dont know the answer to this one and I hope that you guys can help me.

    A truck is driving on a curve which way will the truck fill over. Will it fill to the outside of the curve or to the inside.Please consider that the roads could be in different condtions including rain or snow.

    I did ask someone who is smart and he said that it could go either way but was not sure.
    Is this some kind of trick question? Isn't the answer obvious?
    The answer of this question has been know from the times of Newton. And even then they didn't have any trucks.

    Your smart friend who wasn't sure perhaps is not a candidate for Mensa...
  9. Standard member uzless
    The So Fist
    20 Feb '07 18:47 / 1 edit
    Originally posted by FabianFnas
    Is this some kind of trick question? Isn't the answer obvious?
    The answer of this question has been know from the times of Newton. And even then they didn't have any trucks.

    Your smart friend who wasn't sure perhaps is not a candidate for Mensa...
    While I agree the truck will fall to the outside, I think it is also conceivable that the truck could fall to the inside if the curve has sufficient slope, the truck has a high centre of gravity, and the truck is moving at a rate slow enough to allow the truck to tip over toward the inside of the curve.


    If his friend was thinking in these terms, maybe his exclusion from Mensa is abit premature
  10. 20 Feb '07 19:29
    Originally posted by uzless
    While I agree the truck will fall to the outside, I think it is also conceivable that the truck could fall to the inside if the curve has sufficient slope, the truck has a high centre of gravity, and the truck is moving at a rate slow enough to allow the truck to tip over toward the inside of the curve.


    If his friend was thinking in these terms, maybe his exclusion from Mensa is abit premature
    I don't think anyone would build a road with such a profile that a ordinary stop of traffic would make vehicles af any kind to fall on their side.

    But I agree that even the smartest of people could hesitate to give a definite answer, only because they evaluate also the most remote possibilities up to the level of weather God exists or not.

    But the road constructor that builds roads that makes trucks fall inward in curves when stopped is not clever enough to pass the entrance test of Mensa.
  11. Standard member uzless
    The So Fist
    20 Feb '07 20:08
    Originally posted by FabianFnas
    But the road constructor that builds roads that makes trucks fall inward in curves when stopped is not clever enough to pass the entrance test of Mensa.
    To that, I will concur.
  12. 20 Feb '07 22:51
    Originally posted by XanthosNZ
    http://en.wikipedia.org/wiki/Fictitious_force#Circular_motion

    You are confusing your frames of reference.
    I don't think so -- as Wikipedia says, the truck, which is moving in a non-inertial frame of reference, experiences (fictitious) centrifugal force, which from the frame of the truck seems to push it toward the outside of the curve. A bystander does not notice any centrifugal force, as he is in an inertial frame of reference and does not see any fictitious forces, but we are not talking about bystanders falling over.
  13. Standard member XanthosNZ
    Cancerous Bus Crash
    21 Feb '07 03:24
    Originally posted by GregM
    I don't think so -- as Wikipedia says, the truck, which is moving in a non-inertial frame of reference, experiences (fictitious) centrifugal force, which from the frame of the truck seems to push it toward the outside of the curve. A bystander does not notice any centrifugal force, as he is in an inertial frame of reference and does not see any fictitious forces, but we are not talking about bystanders falling over.
    The truck doesn't recieve a force outwards it's just that the inertia of the truck means that it wishes to continue in a straight line. Centrifugal force doesn't exist.
  14. 21 Feb '07 03:53 / 1 edit
    The centirfugal effect exists, however, because the tangent always points outward, and hence the "straight line" pushes the object outward on the curve.

    It may, however be negated by other things, such as the surface being pitched towards the center, and friction of the tires against the road enabling the vehicle to travel in the direction the tires are pointing better.

    Old playgrounds often had an interesting attraction.. a sort of disk-shaped object set up so it can rotate freely around the central pole, and some bars on the outside to hold onto. Many a kid would attempt to reach the center while it was spinning (myself included), but the closer you got to the center, the stronger the "pull" outward. This became even more powerful as the device spun faster.

    Vehicles going around a curve experience a similar phenomena, even if it is based on inertial resistance to the desired movement, rather than a force perse.
  15. Subscriber AThousandYoung
    It's about respect
    21 Feb '07 04:30
    Originally posted by geepamoogle
    The centirfugal effect exists, however, because the tangent always points outward, and hence the "straight line" pushes the object outward on the curve.

    It may, however be negated by other things, such as the surface being pitched towards the center, and friction of the tires against the road enabling the vehicle to travel in the direction the tires ...[text shortened]... en if it is based on inertial resistance to the desired movement, rather than a force perse.
    You make it sound like merry-go-rounds no longer exist.