Answer:
Explanation:
We can solve this problem using conservation of angular momentum.
The angular momentum is
where is the position and
the linear momentum.
We also know that the torque is
but, as the linear momentum is this means that is parallel to the velocity, and the first term must equal zero
so
But, as the only horizontal force is the tension of the string, the force must be parallel to the vector position measured from the vertical rod, so
this means, for the angular momentum measure from the rod:
that means :
So, the magnitude of initial angular momentum is :
but the angle is 90°, so:
We know that the distance to the rod is 0.750 m, the mass 2.00 kg and the speed 5 m/s, so:
For our final angular momentum we have:
and the radius is 0.250 m and the mass is 2.00 kg
but, as the angular momentum is constant, this must be equal to the initial angular momentum