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Homework Help: Find the angle between the velocity and the total acceleration

  1. Jun 19, 2006 #1
    A point moves along the arc of a circle of radius R .It's velocity depends upon the distance covered as v=a*s^1/2 where a is a constant .Find the angle between the velocity and the total acceleration vector as a function of distance.
  2. jcsd
  3. Jun 19, 2006 #2
    The solution turns out to be a first order differenetial equation

    Since V = a*sqrt(s) where s is the distance traveled

    we can relate s to the radius and the angle subtended

    s = r*theta (just basic geometry here)

    so V = a*sqrt(r*theta)

    From basic kinematics

    V = r*thetadot

    Thus we have

    r*dtheta/dt = a*sqrt(r*theta)

    By using separation of variable it is possible to solve for theta as an explicit function of time. In this case the initial condition is going to be the initial angle which you can assume is zero as it is simply a reference loctation.

    If you want to know theta as a function of distance, then this really isnt much of a problem because theta = distance/radius
    Last edited: Jun 19, 2006
  4. Jun 20, 2006 #3
    Abercrombie, the angle to be determined in the OP's post is the angle between net acceleration and velocity of the object, and not the angle subtended at the centre as a function of time.

    Abhijit, what are your thoughts on the problem ? Please show your attempt thus far .
    Just to get you started, what are the different types of acceleration associated with the particle in question ? So what is the net acceleration (remember acceleration is a vector) ? How is the velocity directed ?
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