Solving Tetherball Problem: Find Tension & Angle θ

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Homework Help Overview

The problem involves a .3 kg ball attached to a 50.0 cm string, completing 2 circles per second. Participants are tasked with finding the tension in the string and the angle θ that the string makes with the horizontal.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants discuss the relationships between tension, gravitational force, and centripetal force, using equations involving θ, radius, and velocity. Some express uncertainty about how to proceed due to multiple unknowns.

Discussion Status

Some participants have provided hints about using the relationships between the variables and suggested dividing the equations to simplify the problem. Others are exploring the implications of the angle θ and its relationship to the radius and length of the string.

Contextual Notes

There is a mention of the need to clarify the definitions of the variables involved, particularly the radius in relation to the angle θ. Additionally, one participant notes the age of the thread and suggests starting a new discussion for more effective help.

ybgl
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Homework Statement


A .3 kg ball is attached to a string that is 50.0 cm in length, and completes 2 circles every second. Find the tension required to whirl the ball with the given constraints and also find the angle θ

2. The attempt at a solution
I only have that Ftcosθ = Mg and that mv^2/r = ftsinθ
I don't know where to go from there since all I have is the length and mass because to find the radius it is r=Lsinθ which I cannot find without θ...
 
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ybgl said:

Homework Statement


A .3 kg ball is attached to a string that is 50.0 cm in length, and completes 2 circles every second. Find the tension required to whirl the ball with the given constraints and also find the angle θ

2. The attempt at a solution
I only have that Ftcosθ = Mg and that mv^2/r = ftsinθ
I don't know where to go from there since all I have is the length and mass because to find the radius it is r=Lsinθ which I cannot find without θ...
Welcome to PF!

This is just an algebra problem now. You have done the physics!

2 equations. 2 unknowns. Solve. Hint: try dividing the two equations.

AM
 
Last edited:
I have tried, it gives me (g)(r)sinθ/cosθ=v^2 which is 3 unknowns since I don't know radius, velocity, or θ
 
ybgl said:
I have tried, it gives me (g)(r)sinθ/cosθ=v^2 which is 3 unknowns since I don't know radius, velocity, or θ
You can work out r from L and θ. θ is the downward angle that the tether makes as measured from the horizontal, so r = Lcosθ. Just substitute into your equation.

v can be determined from the period and radius. Or you can just use mω2r for centripetal force.

AM
 
Andrew Mason said:
You can work out r from L and θ. θ is the downward angle that the tether makes as measured from the horizontal, so r = Lcosθ. Just substitute into your equation.

v can be determined from the period and radius. Or you can just use mω2r for centripetal force.

AM
And where do the solution go from here .Kind of stuck somewhere
 
Welcome to PF, @Lesleyanne :smile:

This thread is over 8 years old, so it's best if you start a new thread here in the Homework Help, Introductory Physics forum and show your work on your problem. That's the best way to get tutorial help with your schoolwork here. Thanks.
 

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