Recent content by Johnny0290

  1. J

    Torque, angular momentum, moment of inertia

    Oh it was supposed to be L not R. I=[(1/12) * (1.2) * (1.6^2)] + [(2) * (.4) * (.4^2)] I=.384 KE=W=(.5)*(.384)*(25^2) W=120 Does this look good? Thank you for your help!
  2. J

    Torque, angular momentum, moment of inertia

    Okay so I could say that the change in kinetic energy is equal to the work done on the rod by the torque.KE_rotational=.5 * I * omega^2 F=ma T=m * omega^2 * r 100=(.4) * (omega^2) * .4 omega=25 rad/sec Not sure if I found omega correctly. This is the max radial velocity before the string...
  3. J

    Torque, angular momentum, moment of inertia

    I=(1/12)MR^2+2mr^2 So do I use work = torque * theta to find work in this situation? F=ma F=m * omega^2 * r 100=(.4) * (omega^2) * .4 omega=25 rad/sec F=ma F=m * R * alpha 100=(.4) * (.4) * alpha alpha=625 rad/sec^2 omega^2 = omega_0^2 = 2*alpha*theta theta=0.5 radians...
  4. J

    Torque, angular momentum, moment of inertia

    Homework Statement Consider a hollow tube of mass M = 1.2 kg and length L = 1.6 m that rotates about an axle through its center and perpendicular to its length. Inside the tube are two masses, m_1 = 0.4 kg each. These masses are initially held a distance d = 0.8 m apart by a string and...
  5. J

    Calc Forces on Hinge for Dynamically Loaded Stick

    Homework Statement In this problem we want to learn a little bit about what is sometimes called dynamical loading. Our simple system consists of a uniform stick of length L and mass M hinged at one end. We would like to calculate the forces on the (frictionless) hinge when the stick is...
  6. J

    How Accurate Can an Atwood Machine Measure Gravity?

    Homework Statement Consider the Atwood's machine of Lecture 8. We wish to use this machine to measure our local acceleration of gravity with an accuracy of 5% [i.e. (Delta g)/g = 0.05]. To begin, suppose we let the mass m_1 fall through a distance L. 3.1 Find an expression for the...
  7. J

    Circular Motion and Newton's Seconds Law (Calculus)

    Wow thank you so much... so far it's working out.
  8. J

    Circular Motion and Newton's Seconds Law (Calculus)

    Homework Statement Consider a bead of mass m that is free to move around a horizontal, circular ring of wire (the wire passes through a hole in the bead). You may neglect gravity in this problem (assume the experiment is being done in space, far away from anything else). The radius of the ring...
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