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If gravity were to double, what would that mean for automobiles?

  1. Feb 20, 2007 #1
    I'm on another forum debating the topic, and it's been quite a while since I've taken a physics course.

    Say, for whatever reason, the acceleration of gravity doubled. So now the vehicle would have twice the weight, but the same mass. How would that affect the acceleration of an automobile on a horizontal plane?

    I would think it would have to mean it would accelerate slower mainly due to increased friction, but there are others saying the increased weight would actually cause it to accelerate more quickly and corner better due to increased friction.

    It hasn't really been discussed, but wouldn't this double gravity also cause the motor to spin slower, and require more torque to spin the drive train, wheels, tires, etc? All of which would result in the vehicle accelerating slower than at normal gravity.
  2. jcsd
  3. Feb 20, 2007 #2
    Well if gravity were to double the cars would travel more slower due to the double gravity pulling down on it. And with double gravity comes double the thus to even drive outta the driveway. This would cause the car too use up more and more gas. Second thought there may not even be life with double. And if you wanna be more direct with it, double gravity could prevent many elements from being prevented that we see today. So yeah it's kind of a mind boggler.
    Last edited: Feb 20, 2007
  4. Feb 20, 2007 #3
    The issue of life and such is a whole other ball of wax.

    I'm just asking in a theoretical world with 2X gravity, say the car could be autonomously driven for the sake of argument.

    The only thing that made a little sense from the counter argument was the effect of spoilers pushing cars down to increase the friction of tires, to increase grip, so faster turns can be made.
  5. Feb 20, 2007 #4


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    I think the main difference would be that you'd have to inflate your tires twice as much :tongue:
  6. Feb 20, 2007 #5
    It'd be great, twice as much traction.. :wink:
  7. Feb 20, 2007 #6
    When g doubles, the car would have more traction, acceleration is unchanged. The gravity does'nt change the engine very much. One thing that can be important is the air drag because the air would be twice as dense.
  8. Feb 20, 2007 #7


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    Just because gravity doubles, does not mean everything else doubles up too. If gravity were to increase by a factor of two, it would be harder to keep a constant speed because of the speed lost to friction, but it would be easier to bake, and slow down.
  9. Feb 20, 2007 #8


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    Not necessarily. It would depend on how much stuff there is in the atmosphere. Look at the moon. There's almost nothing, while g_moon is about 1/6 g_earth.
  10. Feb 20, 2007 #9
    Going down hills would be great, going up hills would be like driving a milkfloat when it's battery is low! You'd need to increase the horsepower of cars somewhat to counter the problem of hills but going down hill and cornering you'd be able to go faster due to increases grip on the roads. Hand break turns would become a lot safer. The increase of friction between the car parts would be small compared to the increase in road grip.
  11. Feb 20, 2007 #10


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    and twice the rolling resistance. (bearings ain't perfectly friction free.)
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