Yo-yo Dynamics: Stopping Time Calculation

[Gary531]

A yo-yo is spun from rest by pulling on the string with a constant tension of 2.0 N. The radius of the inner rod on which the string is strung around is 5.0 cm. The tension is applied 5.0 seconds after which the yo-yo is observed to spin with an angular velocity of 15 rad/sec.

Now you press your finger against the outer rim of the yo-yo (which has a radius of 4.0 cm) to bring it to a stop. You apply a constant force of 2.0 N directed perpendicular to the rim of the yo-yo. Tension is no longer being applied, and the coefficient of kinetic friction between your finger and the edge of the yo-yo is 0.80.

How long does it take for the yo-yo to come to a stop?

 

[collinsmark]

Hello Gary531,

Welcome to Physics Forums!

A yo-yo is spun from rest by pulling on the string with a constant tension of 2.0 N. The radius of the inner rod on which the string is strung around is 5.0 cm. The tension is applied 5.0 seconds after which the yo-yo is observed to spin with an angular velocity of 15 rad/sec.

Now you press your finger against the outer rim of the yo-yo (which has a radius of 4.0 cm) to bring it to a stop. You apply a constant force of 2.0 N directed perpendicular to the rim of the yo-yo. Tension is no longer being applied, and the coefficient of kinetic friction between your finger and the edge of the yo-yo is 0.80.

How long does it take for the yo-yo to come to a stop?

Two questions:

(1) Are you sure you got the dimensions right? It sounds like a very odd yo-yo with an inner-rod radius of 5.0 cm, and an overall-outer radius of 4.0 cm.

(2) How long do you think the yo-yo takes to come to a stop?