What is the speed of the discus at release?

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Homework Help Overview

The problem involves calculating the speed of a discus at the moment of release, based on the thrower's motion in a circular path. The context includes parameters such as the diameter of the circle and the time taken for one complete revolution.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationship between angular velocity and linear velocity, questioning the correct interpretation of the radius in relation to the diameter. There are attempts to reconcile differing results based on the radius used in calculations.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and the calculations involved. Some guidance has been offered regarding the formula for circumference, but there is no clear consensus on the correct approach or resolution of the discrepancies in results.

Contextual Notes

There is confusion regarding the radius used in calculations, as well as the accuracy of the problem statement itself. The original poster expresses concern over receiving different results than expected, indicating a potential misunderstanding of the problem setup.

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Homework Statement


To throw the discus, the thrower holds the discus with a fully outstretched arm and makes one revolution as rapidly as possible to give maximum speed to the discus at release. The diameter of the circle in which the discus moves is about 1.8 . If the thrower takes 1.1 to complete one revolution, starting from rest, what will be the speed of the discus at release?



Homework Equations


I am not sure where to begin. I know that angular velocity=change of theta/change in time.
Velocity=angular velocity*radius.

The Attempt at a Solution


I keep on getting 5.14 m/s. The answer given by the computer is 10 m/s. The only way that I can get 10 m/s is if you use r=1.8 m. I thought the radius would be half the diameter of the circle. What am I missing and what did I do wrong?
 
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Remember the circumference of a circle is 2 pi r
 
I see that but it still leads to (2*pi*.9)/1.1 s=5.14 m/s. If you use 1.8 as the radius then it works out to 10.28 m/s. I have already missed this question in my homework so I am just trying to figure how they got what they got.
 
Yes you're right - looks like they made a mistake in the question.
 

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