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Grade 11Mechanics

a fan is running at 3000 rpm. It is switched off.It comes to rest by uniformly decreasing its angular speed in 10 seconds.The total number of revolution in this period.

Aadesh Kumar

8 Years agoGrade 11

3 Answers

Arun

8 Years ago

Dear Aadesh

thanks= 500 - 250 = 250 rotations.²= 50* 10 + 0.5 (-5) 10 $\Theta$ So,²t $\alpha$ t+ 0.5_o= w $\Theta$ Now,²= – 5 rotations / s $\alpha$ t, $\alpha$ +_oSo, w = 0 = wtime = 10 seconds= 300 rpm = 3000 /60 rotations per second = 50 rps_oGiven , wHi,

Regards

Arun (askIITians forum expert)

Arun

8 Years ago

thanks= 250 rotations.²= 50* 10 + 0.5 (-5) 10 $\Theta$ So,²t $\alpha$ t+ 0.5_o= w $\Theta$ Now,²= – 5 rotations / s $\alpha$ t, $\alpha$ +_oSo, w = 0 = wtime = 10 seconds= 3000 rpm = 50 rotations per second_oGiven , wHi,

Mohit Jaiswal

7 Years ago

3000/6=50 rps . wf=wi+ (alpha)t

0=50+(alpha)10

-alpla×10=50

Alpha=-5

S=ut+1/2at^2

S=50×10 +1/2×-5×10×10

S=500-250

S=250

So answer is 250 revolutions

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