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physics question

Discussion in 'Miscellaneous' started by johncarterminime2, Jul 29, 2013.

Mods: BlueLuigi
  1. johncarterminime2

    johncarterminime2 Shopkeep Stealer

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    I'm 16 and I was wondering, If a car or similar wheeled vehicular object was accelerating at +50 mph-per second and you suddenly cut the power, would it keep accelerating for a few seconds or would it what, I don't understand what would make it keep accelerating for a short time and I can't imagine it would immediately stop its acceleration
     
  2. Kouji

    Kouji Cold, Uncaring, Sadistic, Evil and Cruel Meanie Administrator Global Moderator Forum Moderator Tester
    1. MOLEing Over Large Estates - [MOLE]
    2. REKINS OF SEAS: Super Crew of Ultimate Havoking 2: Return of King of KAG: Chapter 420blazeit - REKIN

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    Acceleration would be the rate of the velocity changes. If your car was accelerating and you cut the power, acceleration would become negative (because you're speed isn't increasing any faster because due to outside forces like friction and air resistance causing a decrease in acceleration). Since acceleration is decreasing, while your velocity is still positive (since your car is still going forward due to momentum), your car will slow down.

    Additionally, there are better people to ask this question, like your high school math teacher.
     
    Vampire, Contrary and Ej like this.
  3. Retrofit

    Retrofit Kami go bye bye Donator

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    yeah, i wouldn't trust the kag community about academics
     
  4. johncarterminime2

    johncarterminime2 Shopkeep Stealer

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    So if it was accelerating at +50 mph-per second and cut the power and someone was in it, they would slam they're head on the dash due to the acceleration change
     
  5. Furai

    Furai THD Team THD Team Administrator

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    No, they wouldn't. Unless the opposing forces (like friction and air resistance) were really high but this is unlikely in the normal conditions.
     
  6. johncarterminime2

    johncarterminime2 Shopkeep Stealer

    Messages:
    54
    I don't get it, if your accelerating at +50 mph a second and it immediately stops accelerating shouldn't the change cause something similar?
     
  7. starting with "I'm 16" wasn't a fortunate beginning as you have been explained Newton physics by that age

    also what Kouji said

    a=delta v/delta t
    if delta v<0
    then a<0 as well
    if your acceleration is lower than 0 it basically means that the object is slowing down, it doesn't stop

    alternatively:
    F=ma
    a=F/m
    somewhat answers your question as well (since your F=0 when power is cut off)
    Although it's a scrappy explanation because, as Kouji said, the car would be slowing down because of friction

    if there was no friction at all (eg. you have a magic car that's driving in vacuum) it would maintain the speed it had while you cut off the power (Newton's I law) and that's where you could apply the a=F/m formula


    i think all i said is right but, it often isn't so feel free to correct me



    oh god i got ninja'd by a couple of people, did you sleep through every single physics class
     
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  8. lavalord

    lavalord Haxor Staff Alumni Donator Tester

    Messages:
    672
    Acceleration /force has already been explained here, so I will just continue a bit.

    In physics jerk is a measure of acceleration per time such that j=a/t.

    Acceleration is felt by a body as a force, hence pressure.

    Jerk can be felt as the change in this pressure. For example a passenger in an accelerating vehicle with zero jerk will feel a constant force from the seat on his or her body; whereas positive jerk will be felt as increasing force on the body, and negative jerk as decreasing force on the body.

    In your example, a passenger is traveling with an acceleration of 50m/s/s. At an instant this acceleration drops to zero and then becomes negative. So lets say 1 second after the power is cut, the acceleration is -5m/s/s. Then the Jerk over this 1 second would be -55m/s/s/s.

    So you would feel a rapid decrease of pressure on your body over that 1 second.
     
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