A potters wheel is attached to an electric motor that increases its angular velo

Question

      A potters wheel is attached to an electric motor that increases its angular velocity from zero to 15 rad/s in 1 minute. Calculate its angular acceleration, and the total number of revolutions it undergoes during this time.

2- For the next two parts, consider the three figures, a), b) and c). The angles from the horizontal are equal in magnitude in cases b) and c). The magnitudes of the three forces are equal.

               a)                                                  b)                                                    c)

B.      If there is NO friction between the crate and the floor, which case will have the GREATEST acceleration? Ans: ____________

C.     If there IS friction between the crate and the floor, which crate will have the MINIMUM acceleration? Ans: __________

D.      The coefficient of static friction is greater than that for kinetic frIction

         True                                 False

Please provide explanation

Explanation / Answer

part 1 )

wf = wi + alpha*t

15 = 0 + alpha*60

alpha = 0.25 m/s^2

theta = 1/2*alpha*t^2

theta = 450 rad = 71.62 rev

part 2 )

part B ) a has greatest accelration

because a = F

b = Fcostha

c = Fcostheta

a

part C )

C has minimum

net force = F -mu*mg ( on a block )

(F/m)(costheta + musin) - mu*g ( B block )

(F/m)(costhea - musinsintheta) - mu*g ( on C block)

part d )

True

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