We sell fans. An engineer asked this question. He wants to buy a fan large enough to cool without being so large it blows paperwork off his desk. Q: At what wind speed will a ceiling fan 10 feet above my desk move a sheet of paper?

  • $\begingroup$ seems to me like nice experiment to do at home. Unless you wish to learn the theory of course. $\endgroup$ – Umaxo May 22 '19 at 16:29
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    $\begingroup$ depends on the location of any other objects on the desk as well... $\endgroup$ – user207455 May 22 '19 at 16:52
  • $\begingroup$ It depends on the position of the paper relative to the fan. If it is directly underneath, the velocity will be different than if it is across the room. $\endgroup$ – Physics May 22 '19 at 17:00
  • $\begingroup$ Besides Solar Mike's really good point (the way the air interacts with the other objects on the desk can highly influence how the air flows), this situation seems a bit odd. Why would the engineer be asking your company if it will lift paper off his desk? That seems like the exact type of question an engineer should be capable of answering. IDK, maybe it's just me, but this is like the exact type of novel problem that is the most fun in engineering/physics. $\endgroup$ – JMac May 22 '19 at 18:17