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Ignoring the reduction in fuel weight as it burns, does the weight on a car's wheels decrease with increasing speeds? If so, by how much and is there a fomula for calculating that? At what speeds does it then become zero?

Qmechanic
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securitydude5
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  • In the relativistic sense, no the mass of the car doesn't change. There may be some amount of lift generated by airflow, but that probably should/would be offset by the airflow pushing down in the car. – Kyle Kanos Mar 01 '19 at 12:16
  • A little bit but only driving eastwards and having latitude dependence. We shall look for duplicates. – Alchimista Mar 01 '19 at 12:20
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    Possible duplicate of Why do cars gain lift while going at a high speed? – Chris Mar 01 '19 at 12:22
  • Possible duplicate of If the ground's normal force cancels gravity, how does a person keep rotating with the Earth? – Alchimista Mar 01 '19 at 12:33
  • https://physics.stackexchange.com/q/299723/ basically answers your question. Just add the the car doesn't stay still but moves and you are done. Unless you consider lifting etc but wouldn't be appropriate. Other answers to questions about weight at poles and equator will do the job as well. – Alchimista Mar 01 '19 at 12:38
  • I am surprised as the only physical way to link weight and speed is through gravity. But perhaps OP was indeed curious about lifting due to aerodynamics. – Alchimista Mar 01 '19 at 17:54
  • If you're concerned about lifting, then it's aerodynamics. If you're concerned about moving over the curve of the earth, then do this: First add the eastward velocity of the earth's surface where you are. Then if you are at orbital velocity (about 5 miles/second) your weight will be zero. The formula for centripetal acceleration is $V^2/R$, where $R$ is earth radius. When that equals $g$, that's your speed. By the way, if you increase $R$ to the moon's distance and decrease $g$ by that ratio squared, you get the moon's speed. Thank Isaac Newton for that. – Mike Dunlavey Mar 01 '19 at 19:06

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The weight of the wheels never decrease. If you are observing a car bouncing off the ground at high speed, it's not the weight decreasing, it's the aerodynamic lift due to Bernoulli's principle of pressure difference due to flow speed. But for specificity, the tire might stretch out radially at high rpm due to centrifugal force, but that's extremely negligible in a practical sense.

TechDroid
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