Centripetal Force Minimum Period Question

[Lax0]

Homework Statement

A boy ties a 3.00kg rock to a 0.70 m string and begins spinning it around in a horizontal circle at a constant speed. If the string will break if the tension is greater than 80.0 N, what is the minimum period for the rock to spinning in a circle. How do i solve this?

Homework Equations

m4∏^(2 ) r/T^2

The Attempt at a Solution

80.0= (3.00)4∏^(2)(0.70)/T^2
T= 1.02

 

[Delphi51]

Welcome to PF!
Looks good. I get a very slightly larger answer; might be worth running it through the calculator again.

 

[anaximenes]

Your equations written as pie squared r instead of pie r squared, i think you did it right but it looks weird

 

[Lax0]

Your equations written as pie squared r instead of pie r squared, i think you did it right but it looks weird

its the equation in the textbook. So can you explain how max tension gets minimum period?

 

[haruspex]

its the equation in the textbook.

Yes, the equation is correct, though it does look odd at first sight.

So can you explain how max tension gets minimum period?

The stone has a certain distance to cover, 2πr, in one period. So minimum period means maximum speed, and that means maximum tension.

 

[anaximenes]

Sorry your right, its so weird seeing pie digitally