Unformatted text preview: Review Exam 3 Physics 2750 1. A puck on a frictionless air hockey table has a mass of 5.0 g and is attached to a cord passing through a hole in the surface as in the figure. The puck is revolving at a distance 2.0 m from the hole with an angular velocity of 3.0 rad/s. The cord is then pulled from below, shortening the radius to 1.0 m. Calculate the new angular velocity (in rad/s) of the puck. 2. A uniform 100‐kg beam is held in a vertical position by a pin at its lower end and a cable at its upper end. A horizontal force (magnitude P) acts as shown in the figure. If P = 75 N, what is the tension in the cable? 3. A thin rod of mass M and length L is suspended vertically from one end. A small piece of clay of mass m is thrown at the rod perpendicular to it with a speed v0 and hits the rod at a distance d > L/2 below the point of support. The clay sticks to the rod and the two of them start rotating together. A) Find the angular speed with which the rod + clay system starts rotating. B) Find the maximum height they will reach with respect to the bottom end of the rod. 4. A mass m1 and a mass m2 are suspended by a pulley that has a radius R and mass M. The cord has a negligible mass and causes the pulley to rotate without slipping. The pulley rotates without friction. The masses start from rest a distance d apart. Treating the pulley as a uniform disk with a moment of inertia ½ MR2, determine the speeds of the two masses as they pass each other. 5. Find the work required to move an Earth satellite of mass m from a circular orbit of radius 2RE to one of radius 3RE. 6. At what height above Earth’s surface is the energy required to lift a satellite to that height equal to the kinetic energy required for the satellite to be in orbit at that height? 7. The pulley shown bellow has radius R and moment of inertia I. One end of the mass m is connected to a spring of force constant k, and the other end is fastened to a cord wrapped around the pulley. The pulley axle and the incline are frictionless. If the pulley is wound counterclockwise so that the spring is stretched a distance d from its unstretched position and is then released from rest, find the angular speed of the pulley when the spring is again unstretched. ...
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 Spring '10
 Kostzin
 1.0 M, 2.0 m, new angular velocity, frictionless air hockey, angular speed, 3.0 rad

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