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Homework Help: Conceptual question on force

  1. Nov 5, 2004 #1
    Okay, I guess this is a conceptual problem that I am having with this one. let me explain the problem, firstly:

    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 dgrees 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 forse required to pull on the chain in order that the car moves at a constant speed

    b) find the tension in the chain.

    Here's my problem:
    We are pulling it up to the bed of the truck, and the chain is wrapped around a cylindar, then connected to the car. Does it matter that the chain is wrapped around a cylinder? wouldn't it just rotate? would that change the force needed to pull it up? This doesn't sound like a pulley to me, which is the only way i see it making a difference. I know this may seem like a weird question to a weird problem, but i'm just sitting here scratching my head unable to move forward! Haha, any help here would be appreciated!
  2. jcsd
  3. Nov 5, 2004 #2


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    How many times is the chain attached to the car? If it's only attached once, then there is no mechanical advantage due to the pulley. If the chain is attached to the car more than once - say a winch hooking from the car over the axle and back to the car - then there is mechanical advantage, and the tension will be smaller.
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