Hybrid Cars

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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
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    Re: Hybrid Cars
    Testing, Niel; always testing. :p
    Now how many 'typos' of mine has no one noticed? Well we don't know 'cause no one noticed them! :D

    The Baseball Principle is the fact that when the ball hits the bat it stops and reverses direction. Upon impact it deforms as the energy changes direction (and some is lost to heat and some is added by the bat force). The idea is that if a car could be constructed like the baseball it would upon impact with another object, deform slightly and then reverse direction - bouncing off instead of crumpling up like tinfoil. Then all you'd have to worry about is the whiplash.

    So far it hasn't been done. (So-called "impact absorbing" bumpers don't.)

    So called impact-absorbing bumpers truly are energy-absorbing bumpers and that is what counts.

    Thanks for the opportunity for a second try!

    <Begin lecture>
    From the bat's point of view, the physics that makes that so difficult to implement in practice is that:
    1. Sometimes the bat breaks! It is under a very large amount of stress that it would not be under if it or the ball were softer.
    2. Nobody is riding on the bat or the ball. It is more than just whiplash. The acceleration forces on the bat as it changes speed are very large, even larger on the baseball.
    3. The bat does not actually change direction. It does not necessarily even stop. It has more mass than the ball.
    4. To work to protect the occupant, the change in velocity without crushing would have to take place over an extended period of time. That translates to an extended distance. Like at least twice the length of the crush zone that would achieve the same reduction in acceleration.

    To apply the baseball principle as a bat, you car would have to be at least twice the weight of all other cars. (I see a Lake Woebegone paradox here.)
    To apply the baseball principle as the ball, you can be any weight in comparison to the bat, and if the impact is between two balls of equal mass and come in with equal speed, they will both end up going backwards at their original speed.
    The bumpers (front and back) would have to incorporate maybe 4 feet of spring (it's back to big cars again, I guess). The lighter, car, if it started out stationary will then go speeding off backwards at at least twice the speed the "bat" was moving at during the collision. If bat car (!) and ball car were moving at the same speed but in opposite directions, then then the ball car will end up moving backwards at more than its initial speed and the bat will keep on moving forward at less than its original speed (assuming that the bat is twice the mass of the ball).
    You will need to have 4 foot side bumpers too.

    And even with all of that, you will still need seat belts and airbags to protect you, only twice as effective as they would have to be with energy dissipating crush zones.

    Would you rather be the bat or the ball in this scenario?

    <End of lecture>.
    SMA SB 3000, old BP panels.
  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
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    Re: Hybrid Cars

    Not sure if anyone answered the original poster's question on the battery pack of a Prius but a Prius pack is only around 1.4Kw. The size of the battery in a non-plug in hybrid doesn't have a whole lot to do with anything. The smaller and lighter the car the smaller the battery has to be. Hybrids only utilize a very small percentage of the pack anyway. Any Toyota hybrid does very well with fuel efficiency compared to a similar non-hybrid vehicle. Whether it is worth the extra cost for a hybrid is always up for debate and that's not one that I like to get involved in. I bought a hybride because it saves on fuel, it's cleaner for the air compared to a non-hybrid, and I like new technology.