Problem 8.40 Part A How large is her torque on the wheelif the diameter of the b
ID: 1784678 • Letter: P
Question
Problem 8.40 Part A How large is her torque on the wheelif the diameter of the bowl is 9.0 cm? A potter is shaping a bowl on a potter's wheel rotating at constant angular velocity of 1.5 rev /s (Figure 1). The friction force between her hands and the clay is 1.6 N total. Express your answer to two significant figures and include the appropriate units. H A r . , sh CO Ttotal = Value | Units Submit My Answers Give Up Figure 1 E of 1 Part B How long would it take for the potters wheel to stop if the only torque acting on it is due to the potters hands? The moment of inertia of the wheel and the bowl is 0.11kg - m? Express your answer to two significant figures and include the appropriate units. HA n A Ge ? t= Value Units Submit my answers Give Up Provide Feedback ContinueExplanation / Answer
torque = r*F*sintheta
D = diameter of the pot = 9cm = 0.09 m
r = radius of the wheel = D/2 = 4.5 cm = 0.045 m
F = frictional force = 1.6 N
r and F are perpendicular theta = 90
torque = 0.045*1.6*sin90
torque = 0.072 Nm <<<--------ANSWER
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part B
firctional torque = I*alpha
firctional torque = -0.072 Nm
angular accelration alpha = (wf - wi)/t
wf = final angular velocity = 0
wi = initial angular velocity w1 = 1.5 rev/s = 1.5*2pi rad/s
t = time interval
-0.072 = 0.11*(0-(1.5*2pi))/t
t = 14.4 s <<<-------ANSWER