Centripetal acceleration fan problem

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SUMMARY

The discussion centers on calculating the maximum distance a spider can safely cling to a ceiling fan blade without losing grip due to centripetal acceleration. The fan operates at 100 revolutions per minute, equating to an angular velocity of 10.47 rad/s. The spider experiences a centripetal acceleration threshold of 0.3g, which translates to 2.94 m/s². The correct calculation reveals that the spider can safely be 1.05 meters from the center of the fan, despite initial miscalculations suggesting 27 mm.

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  • Understanding of centripetal acceleration and its formula: a = ω²r
  • Knowledge of angular velocity and its relationship to revolutions per minute
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  • Ability to convert units and interpret results in the context of physical problems
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Adsy
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Homework Statement


A ceiling fan is turning at a rate of 100 revolutions per minute. A spiders is clinging to a blade of the fan. If the spider experiences a centripetal acceleration greater than 0.3g, it will lose its grip on the blad and be flung off. How far from the centre of the fan can the spider safely go?

Rate = 100 rev/sec

a = 0.3g

r=?

Homework Equations



\omega=\frac{\Delta\theta}{\Delta t}

\omega=\frac{2 \pi}{T}

v= \omega r

T= \frac{2 \pi}{\omega}

a=\frac{v^{2}}{r}

a=\omega^{2}r

The Attempt at a Solution



I've worked out that the time period, T = 0.6s

a=0.3g=2.94 ms^{-2}

then use: \omega=\frac{2 \pi}{T}

\omega=\frac{2 \pi}{0.6} = 10.47 rad s^{-1}

then I rearrange this formula: a=\omega^{2}r

r= \frac{a}{\omega^{2}}

then put in the known values to find r
r= \frac{2.94}{10.47^{2}} = 2.7*10^{-2}m

*fixed*

This is incorrect. What am I doing wrong?
 
Last edited:
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Adsy said:
then put in the known values to find r
r= \frac{2.94}{10.47^{2}} = 2.7*10^{2}m

This is incorrect. What am I doing wrong?

2.7*10^{-2}m = 27mm
 
Oh, that's just a mistake with TeX.
That answer is still incorrect.

The correct answer is 1.05m but how do you work it out?
 
I think there's a mistake in your "correct" solution.
The solution is 27mm.
The problem is rather simple.
Other readers may double check the result.
 
I've asked my friend about this question. He also said the answer is 2.7cm.
Hmm... maybe my textbook has an incorrect solution...
 
Yep. My answer is correct. I've Googled the problem and found other people struggling with the same question. The book is incorrect. Silly Edexcel...
Thanks anyways, Quinzio!
 

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