Question

A fan is designed to last for a certain time before it will have to be replaced (planned obsolescence). The fan only has one speed (at a maximum of 650 rpm),650 rpm), and it reaches the speed in 3.0 s3.0 s (starting from rest). It takes the fan 10.0 s10.0 s for the blade to stop once it is turned off. The manufacturer specifies that the fan will operate up to 1 billion rotations.

Andre lives in a hot climate, works outside of the home from approximately 8:00 am to 5:00 pm, Monday through Friday, does not own an air conditioner, and can't sleep with the fan running. Estimate how many hot days ?hot Andre will be able to use the fan, rounded to the nearest day.

Answer 1

I think there is a mistake, should not he run the fan when Andre is sleeping on hot day? Also the answer depends on the avg number of hours when the phone is on.

for about S hours on weekdays Ans The fan Yuns (on average) time and stopping time the fan at weekend and 20 hrs negleet tarting the time for which We Can (uns is quite a s large for a day Runs at So Can assume that the fan we time 6 So pm or whole The fan operates for SXIS 2X20 - 1IShrs week There fore the fan operates about 16. 3 hrs per day re volution made by the fan in Number f day 6 So rev 6.43 hrs 60 min day 640770 rev day * min hr Number 0f hot days N- I billion rotations N XI0 rev S60.6 days I56 days 6Ч0770 Yev day o of days sRop 195 N