- #1

fruitl00p

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## Homework Statement

A mass m= 4.7 kg is suspended from a string of length L=1.19m. It revolves in a horizontal circle. The tangential speed of the mass is 2.97 m/s. What is the angle between the string and the vertical (in degree.)

## Homework Equations

r= Lsin(theta)

Tension is broken up into x and y components, so Tsin theta=ma(of radius)

and Tcos theta=mg

sin^2theta =1-cos^2theta

## The Attempt at a Solution

I'm having a hard time solving this because of the unknown radius along with the unknown angle!

first I tried T=mg/cos theta; then plugged that into the tension in the x axis, making it tan theta=a(of radius)/g

But the equation for a rad is 4pi^2R/t. And the peiod is another unknown.

This is as far as a I got: tan theta= 4pi^2 Lsin theta/ gt^2

The assignment was due a couple of weeks ago and I didn't get the answer correct. But I have a test coming up and on the practice exam the same problem is on it.

I was told to use quadratic equation to solve for angle, which makes sense but for the life of me, I just can't do it. I don't understand how to use the quadratic equation to solve it. Please someone help me.