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Homework Help: My IIT Problem

  1. Apr 19, 2005 #1
    Question:A body of mass is placed on a smooth horizontal surface. The mass of the body is decreased exponentially with disintegration constant λ. Assuming that the mass is ejected backwards with a relative velocity u.If initially the body
    was at rest, the speed of the body at time t is:
    (a)ue^(-t)
    (b)uλt
    (c)ue^(-λt)
    (d)u{1-e^(-λt)}.
     
  2. jcsd
  3. Apr 19, 2005 #2
    Quick Reply Awaited.
     
  4. Apr 20, 2005 #3

    OlderDan

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    Science Advisor
    Homework Helper

    I guess this does not qualify as speedy, but do you know the rocket equation? What you have is a rocket. Figuring out the speed of a rocket is not trivial, but it all depends on conservation of momentum. A decent explanation is given here.

    http://ed-thelen.org/rocket-eq.html

    The final equation can be written as

    [tex]v(t) = v_0 + uln \left[ \frac{M_0}{M(t)} \right] [/tex]

    In your problem, the initial velocity is zero. If you understand logs and exponentials, you can do the rest.
     
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