A skater is spinning with his arms outstretched. He has a 2 lb weight in each hand. In an attempt to change his angular velocity he lets go of both weights (by just opening his grip). Does he succeed in changing his angular velocity

Respuesta :

Answer:

No

Explanation:

Changing momentum of any kind requires work. Work is a force acting over a distance. While holding the weights at arms length and spinning will create a force (centripetal), there is no radial distance change incurred. Releasing the weights will reduce the force to zero, still no work done and no change in angular momentum.

If he was holding the weights at arms length while spinning and he pull his hands to his chest, there now exists both the centripetal force and a distance in the direction of that force (inward radial) this work will result in an increase in angular velocity as moment of inertia has decreased with the work done.

No, the skater doesn't succeed in changing his angular velocity.

Conservation of angular momentum

The final angular velocity of the skater is determined by applying the principle of conservation of angular momentum as shown below;

Li = Lf

[tex]Ii\omega _i = I_f \omega _f[/tex]

where;

  • Ii is the initial moment of inertia of the skater
  • If is the final moment of inertia of the skater
  • ωi is the initial angular speed of the skater
  • ωf is the final angular speed of the skater

When the skater holds the weight, the momnet of inertia of both arms is the same. Also when the skater drops the weight, the moment of inertia of both arms is still the same. Thus, at any instant, the moment of inertia of the two arms is the same.

To change the angular speed, the initial and final moment of inertia of the two arms must be different. Thus, the skater doesn't succeed in changing his angular velocity.

Learn more about angular momentum here: https://brainly.com/question/7538238