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Running out of hair to yank out! (tension)

  1. Nov 7, 2004 #1
    I've been stuck on this problem all weekend. yes, all weekend. no partying, no hanging, no general fun of any kind. What's so frustrating about this is that i just can't seem to get it started.

    A sedan rolled off the road and needs to be towed. In order to get the car on the tow bed, it is pulled along an incline of 23.1 degrees with a chain wrapped around a frictionless axle, composed of a solid cylinder of mass 58.2kg and a diameter .211m. The car has a mass of 1120kg.

    a) find the force required to pull on the chain in order that the car moves at a constant speed

    b) find the tension in the chain.

    At this point, I would generally say what I know, but after staring at this all weekend, all I KNOW is that I'm running out of hair to yank out! Someone please have mercy on my poor, tortured soul!
  2. jcsd
  3. Nov 7, 2004 #2
    Now take this with a grain of salt, since axles and pulleys have never been my forte, but I think it depends on where the other end of the chain is connected. If it's connected to some tow truck, it shouldn't mater, both of the forces should be the same and equal to the force parallel to the incline necessary to keep the car stationary (you can calculate that as usual from the force of gravity + normal force etc). I think there'd only be a difference if the car was "towing itself" by means of some axle (ie, if the chain looped back). So I pretty much think this is a scare problem that over-provides you with information (the axle can be ignored since it is frictionless).

    But I'm not quite 100% sure; as I said, my axle/pulley understanding is not as great as it could be.
  4. Nov 7, 2004 #3
    This is what i thought at first, but it is scaring me a little more then usual, especially since we JUST covered this in class. I'm with you, though. i don't see how the stupid cylinder would make a difference, lol. it just seems like the only purpose it would serve would be to avoid making an angle that the chain pulls on the car.

    does anyone else have a say on this?
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