Here since both children and merry go round is our system and there is no torque acting on this system
So we will use angular momentum conservation in this

now here we have



Now when children come to the position of half radius
then we will have



now from above equation we have


So the problem ask to calculate the magnitude of the average force applied to the ball if its mass is 0.2kg changes its velocity from 20m/s to 12m/s and the time contact with the ball with the wall is 60 ms. In my calculation the best answer would be 107N.
Answer:
what is the question please?