Centripetal acceleration fan problem

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Homework Help Overview

The problem involves a ceiling fan rotating at 100 revolutions per minute and a spider clinging to one of its blades. The spider's grip is at risk if the centripetal acceleration exceeds 0.3g, and the question seeks to determine the maximum distance from the center of the fan where the spider can safely remain.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the calculations related to centripetal acceleration and the relationship between angular velocity and radius. There is confusion regarding the correct interpretation of the results and the values derived from the equations.

Discussion Status

Multiple interpretations of the calculations are being explored, with some participants questioning the correctness of the original poster's results. There are differing opinions on the final answer, and some participants express uncertainty about the textbook's solution.

Contextual Notes

Participants note discrepancies between their calculations and the textbook's answer, leading to discussions about potential errors in the provided solutions. There is mention of external sources and peer input regarding the problem's resolution.

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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