Question

A large industrial high speed fan is spinning at 480 rpm when the power cord is
accidentally unplugged. Without the power source, friction in the bearings cause the fan to
slow down. The fan blades are 40.0 cm long and spinning in the ccw direction.
a. At what rate (in rpm) is the fan spinning after 30.0s, if the blades make 150
complete revolutions in that time?
b. What is the angular AND tangential acceleration magnitudes at the ends of the fan
blades?
c. If the power cord was not plugged back in, how long (in total) would it take for the
fan to come to rest?
d. How many revolutions would the fan complete in coming to stop?

Answer 1

60 450 -ve ZT Giren - Intial angular velocity (N1)=400 RPM wi=QTINI =251X 480 = 16ta (Date : 1 WIE 50.27 Radis, t=303, Nato se Angular displacement during 80s. 0 = 271X150 = 300 T =0 = 9 421 47 Radt we know that, we=w.tat o - Angular aco? Again, o= widt2t28942.47=50.27*30tLa(30) => a=(942-47-1508.10)=12=-1:26 Rad/e2] in shows angula retardation, prom equation @ we have (2= 50.27+ (-1.26)83 0 => /W 2= 12.47 Rad/A. w2=27N2 = N2 = 6002 = N2= 60x12:47=119.07 2T N2=119.078pm 7 ans fa 6 Tangential accelection = Angular abebration & Ractices Cat=ra=0.408 12 6=9+=0.504 M/S) ngular acch - 1.26 pael/32 mo r e lungo © wow,tatas t = W2-ar =/0-50.27 -20.89s 2 T _1.26 - to = 39.098] ors- © @ before comming rest, oz Witt tat2 Oz= 50'27X39.09 +(-1.26) (39.89j2 Q=1002: 81 Radians Of = 271 N Oz - 1002-8). 159.60 = N2= 277 27 ge will complete = 159 Revolutions before rest) nord) E o Slade 40cm -39.89 € 1,26