How Do You Calculate Radius in Uniform Circular Motion?

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Homework Help Overview

The discussion revolves around calculating the radius of an object in uniform circular motion, given its mass, kinetic energy, and tension in the string. The context involves understanding the relationships between these physical quantities in a circular motion scenario.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the relationships between mass, tension, kinetic energy, and radius. Questions arise about the relevance of gravitational force and how kinetic energy relates to speed and mass. There is also discussion on deriving velocity from kinetic energy and using it to find acceleration.

Discussion Status

Some participants have expressed confusion about the connections between the given quantities and the calculations needed. Guidance has been offered regarding the relationships between kinetic energy, speed, and circular motion. One participant has reported figuring out their approach and is seeking validation of their reasoning.

Contextual Notes

Participants are working under the constraints of a homework problem, which may limit the information available and the methods they can use. There is an emphasis on understanding rather than simply applying formulas.

george256
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A 2.4 kg object attached to a horizontal string moves with constant speed in a circle of radius R on a frictionless horizontal surface. The kinetic energy of the object is 75 J and the tension in the string is 330 N. Find R.
 
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F = ma, & a few others.

Don't just look for the "magic" equation. Think about the quantities you are given and what's asked, How are they related to each other or to related quantities.
 
well i keep thinking i have my mass i know gravity so i should multiply those to get mg then i feel like i should multiply mg with my 330N because that is my tensional force, and i have no clue what to do with the 75 j. Am I going in the right direction though?
 
You don't need the weight, mg.

How is kinetic energy related to speed and mass?

What do you know about circular motion?
 
i can get my velocity from k but with that what do i do?
 
I figured it out thank you so much for the help. I had one of those duh moments when i realized. I will write down what I did so you can tell me if it was the correct and simplest way to go about it if you do not mind. first off i found my velocity using k=1//2mv^2 then i used my force of 330N in f=ma and got my a then i used the circular motion equation a=v^2/r and that was my answer. Does that seem like the correct way to do it?
 
george256 said:
I figured it out thank you so much for the help. I had one of those duh moments when i realized. I will write down what I did so you can tell me if it was the correct and simplest way to go about it if you do not mind. first off i found my velocity using k=1//2mv^2 then i used my force of 330N in f=ma and got my a then i used the circular motion equation a=v^2/r and that was my answer. Does that seem like the correct way to do it?
Looks good !
 

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