k-help/questions-and-answers/tradesman-sharpens-knife-pushing-rim-grindstone-30
ID: 1780742 • Letter: K
Question
k-help/questions-and-answers/tradesman-sharpens-knife-pushing-rim-grindstone-30 -cm-diameter rpm-mass-91671598 MasteringPhysics PARASHAR C HAPTER 07 Hww-Google Chrome Secure https PARASHAR.CHAPTER OT HW Problem 7 71 Problem 7.71 Part A A tradesman sharpens a knite by pushing t agans the rim of a grindstone The 45 cm dameter stone is spinning a1 200 rptm and has a mass of 22 kg The coemcient of kinesic friction between the knte the stone loses 10% of its speed in 10 Sofgnnding what is the nonce with which the man presses the knite against the stone? Express your answer to two signiticant figures and include the appropriate units and the stone is 0.20 My Answers Incorrect; Try Again; 6 attempts remaining ContnueExplanation / Answer
a] change in speed = 200*0.10 = 20 rpm = 20*2pi/60 = 2.094 rad/s
average angular acceleration alpha = 2.094/10 = 0.2094 rad/s^2
Friction*r = i*alpha = 0.5mr^2*alpha
friction = 0.5 m r alpha = 0.5*22*0.45/2*0.2094 = 0.5183 N
Normal N = Friction/u = 0.5183/0.20
= 2.6 N answer
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