Problem # p053

Conservation of Angular Momentum

A ball is located at position A on a rod which can freely rotate around an axis located at point 0 pointing out of the picture. For the first part of this problem the ball is held at point A by a string while the rod is rotating.

  1. What is the velocity of the ball while at position A if the angular velocity of rod/ball is ω = 2 rad/sec ?

  2. What is the force the string has to exert onto the ball if the ball is moving on a circle with a radius of 5cm as shown in the picture.

  3. Suddenly the string is cut, the ball slides outward on the rod until it reaches a distance of 25 cm from the axis of rotation, see picture. Assuming that the tangential forces onto the ball during this motion are negligible ( i.e. the rod is of negligible mass and nobody is exerting a torque onto the axis of rotation) , what is the velocity [m/sec] of the ball once at position B ?

Hint : No gravity for this problem.