Trial Time (s) 1 2.4 2 2.6 3. You just finished your Saturday morning run and...

 

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Trial Time (s) 1 2.4 2 2.6 3. You just finished your Saturday morning run and are sitting on a park bench resting. You see a little girl playing with one of those rotating platforms that several kids could sit on and be spun around by their parents. But, there is no one sitting on the platform and the little girl is spinning it on her own. She runs around in circles, faster and faster until she can't make it go any faster, then she lets go. She stares at it spinning slower and slower until it comes to rest. Then, she does it all over again, and again, and again, a total of 5 times. You 3 2.3 4 2.3 realize that without knowing it the little girl is doing an experiment that you could use to estimate the frictional torque being exerted by the central support on the rotating platform. Since you were out running you had your stopwatch on and you timed the last 4 of the little girl's trials (shown in the table). You estimate that the platform was rotating at 0.20 +0.03 rev/s each time the girl let go of it, and that the rotational inertia of the platform is 14020kg.m. a. Which of the three kinds of experiment is this? How do you know? What major feature of this kind of experiment is missing? b. Estimate the frictional torque being exerted on the platform by first estimating the rotational acceleration of the platform. Include the uncertainty in your estimate of the frictional torque. c. Describe any assumptions that you made in your mathematical procedure. Trial Time (s) 1 2.4 2 2.6 3. You just finished your Saturday morning run and are sitting on a park bench resting. You see a little girl playing with one of those rotating platforms that several kids could sit on and be spun around by their parents. But, there is no one sitting on the platform and the little girl is spinning it on her own. She runs around in circles, faster and faster until she can't make it go any faster, then she lets go. She stares at it spinning slower and slower until it comes to rest. Then, she does it all over again, and again, and again, a total of 5 times. You 3 2.3 4 2.3 realize that without knowing it the little girl is doing an experiment that you could use to estimate the frictional torque being exerted by the central support on the rotating platform. Since you were out running you had your stopwatch on and you timed the last 4 of the little girl's trials (shown in the table). You estimate that the platform was rotating at 0.20 +0.03 rev/s each time the girl let go of it, and that the rotational inertia of the platform is 14020kg.m. a. Which of the three kinds of experiment is this? How do you know? What major feature of this kind of experiment is missing? b. Estimate the frictional torque being exerted on the platform by first estimating the rotational acceleration of the platform. Include the uncertainty in your estimate of the frictional torque. c. Describe any assumptions that you made in your mathematical procedure.