Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Personal development?

  1. May 17, 2006 #1
    i trust you have all seen american inventor, and if not go look at the car seat on there because that is what this has to do with

    its bad, because the force has to go somwhere and probably it will hurt the child in the long run, but what if we could lower the amoung of force

    consider the following

    f= ma

    a= f/m

    my thought... add more weight, (m), and by adding more weight you will directly reduce A, and A will directly impact F.
    my father is not so sure (mechanical engineer as well) he says there are more than one system, but even effecting one system you impact the second.

    --- first year college so im not 100% content.
  2. jcsd
  3. May 17, 2006 #2
    The deceleration of the car seat does not depend on the mass of the car seat, it is tied into a bigger system (the car itself); therefore, EVERYTHING inside the overall system (the car) will decelerate at the same rate as the car is suddenly impacted during the car accident.
  4. May 17, 2006 #3
    but im concentrating on the force acting on the car seat. not sure if you have seen the seat but it swings. if not google immage it, because on impact it flips. were worried about what will happen to all that force upon impact of the collision. i believe that the best way to decrease force on the car seat will be to add more weight.
  5. May 17, 2006 #4
    The car seat swings?

    Based on your description, don't put too much worry into it, that sounds like something that would never get approved by the road safety association.

    Trust me, you do NOT want a car seat swinging around the inside cabin of the car during an impact, it will kill the child.
  6. May 17, 2006 #5
    lol i agree, unless it can be perfected, and this guy is working on perfecting it. intuitively this sounds like a wonderful idea, but we all agree that it is flawed. i feel it can be perfected with somthing as simple as more mass.
    am i wrong?
    im not worried about if it will be aproved, its just killing me mentaly. lol you know the feeling.
  7. May 17, 2006 #6

    :bugeye: :eek: How can you say 'intuitively' that a car seat that swings around with a child in it by some no-name inventor is a 'wonderful idea'?

    Don't you think the car seat manufacturers that pour millions of dollars into research would have thought about that by now?

    Think about your statement. You want to add more mass? You are an engineering student. Who is going to use this car seat? A woman is. You have to design this car seat so that she can carry it and her child around. Unless you increase the weight of the car seay by orders of magnitude the change in mass will be insignificant. Why would you want to propose such an idea?:grumpy:

    I saw 5 min of that show. The people had inventions that were flat out laughable. :rolleyes:
  8. May 17, 2006 #7
    no i agree it would be bulky, but intuitively the science makes sense. instead of having to worry about the childs head smashing against somthing, the seat acts as a mothers womb and spins. look im not saying this seat will ever see the light of day, im more interested on what it would take to work.
    as far as physics goes
  9. May 17, 2006 #8


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Cyrus, it swings about a fixed axis, I think.

    http://www.makezine.com/blog/img413_572.jpg [Broken]

    Instead of a linear deceleration, the baby is going to feel g-forces from the swinging. I'm not sure I get exactly how this works, simply by looking at the picture. Are there rotational dampers on it ?
    Last edited by a moderator: May 2, 2017
  10. May 17, 2006 #9
    ya the inventions on the show are quite funny, but it was interesting to watch to see what would come up.
  11. May 17, 2006 #10
    :rofl:They suck that poor kid into a flower pot! :rofl:

    So let me get this striaght, now the poor child will be subjected to a Rotation (centripetal acceleration) AND a linear deceleration during the accidet. :rolleyes:

    The poor kid will black out when that thing starts swinging and possibly get bloodshot eyes.
    Last edited: May 17, 2006
  12. May 17, 2006 #11
    keeping in mind that i am a still in my first year

    more mass wouldnt lower the damages from this?
  13. May 17, 2006 #12
    What difference does mass make when it is tied to the car itself? The entire system (car, people, baby, carseat) will all decelerate together at the same rate because the people are 'tied down' to the car by restraints.

    You can (i) decelerate at the same rate as the car, or (ii) not wear a seatbelt and fly out the windsheld at a different rate.
  14. May 17, 2006 #13
    in my mind im thinking if secured properly, this should (with the proper math) be able to help.
    i do trust your judgement, im just wishing i could understand it. maybe when i actualy take physics next semester ill get a better idea, but right now im just running off of information i have gathered online
  15. May 17, 2006 #14
    If I were going to design a car seat for a baby, I would have a spring system so that when the car decelerates, the springs dampen out the sudden deceleration by increase the time it takes before the baby comes to a stop, because now the baby is not fixed to the car (he and his seat are floating). I would not recomend swinging a baby around an axis, fixed or not.

    In any event, just put the baby on the dashboard, its good for the little guy. Cup holders are good places to keep them too. :rofl:
    Last edited: May 18, 2006
  16. May 18, 2006 #15

    Huh? This poor kid is moving forward with the car. Rotation or not, he has to decelerate in the forward direction. If this thing starts rotating, that does not mean he wont have a component of deceleration in the forward direction. Actually he will have a deceleration force in the forward direction in addition to a force due to induced rotatation. (However the hell that's possible)

    *If this were an ideal case, he would not even rotate in the first place! What would cause his rotation due to a linear deceleration? Is the inventor going to put the COM of the baby different from that of the fixed axis of rotation, so that the baby can barf due to road perturbations all along the way?

    This idea is as stupid as the show. :rolleyes:
    Last edited by a moderator: May 2, 2017
  17. May 18, 2006 #16


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The linear deceleration is reduced by the horizontal component of the swing (during the first half of the swing).
  18. May 18, 2006 #17
    I do not follow you. :confused:
    Last edited: May 18, 2006
  19. May 18, 2006 #18


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Look at the limiting case. When the car stops instantaneously, the seat swings forward. The car frame had an infinite deceleration, the baby had a large, but finite deceleration.

    In reality, the swinging seat might help in the most catastrophic head-on cases, but only make things worse for minor events.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook