# Angular acceleration of a Propeller

1. Mar 4, 2008

### clope023

[SOLVED] angular acceleration of a Propeller

1. The problem statement, all variables and given/known data

An airplane propeller is rotating at 2000rev/min .

$$\omega$$z = 209rad/s

How long in seconds does it take for the propeller to turn through 40degrees?

2. Relevant equations

$$\theta$$ = 1/2$$\omega$$t

$$\omega$$z = d$$\theta$$/dt

3. The attempt at a solution

40degrees = (2$$\Pi$$/360degrees) = .698rad

209rad/s = .698rad/t

209rad/s(t) = .698rad

t = .698rad/209rad/s

t = .0033s wrong

I'm sure I'm using the right equations, does anyone know what I'm doing wrong?

any help is appreicated, I think I'm missing something obvious just not sure what it is.

2. Mar 4, 2008

### Staff: Mentor

Looks OK to me. Why do you think it's wrong?

3. Mar 4, 2008

### clope023

masteringphysics told me it was wrong

4. Mar 4, 2008

### clope023

oh for the love of God, I entered .003 instead of .0033 and they counted it wrong, I hate masteringphysics, thanks for checking anyway Doc Al

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