Please help!!! 1) A grinding wheel in the shape of a uniform solid disk of radiu
ID: 1295528 • Letter: P
Question
Please help!!!
1) A grinding wheel in the shape of a uniform solid disk of radius 35 cm and mass 1.8 kg is initially spinning at 1200 rpm about its center of mass before it is switched off. It takes the wheel 4 sec to come to rest
a)How many revolutions does the wheel make from the instant that it is switched off to the instant it comes to rest? Answer must be 40 rev
b) What is the magnitude of the frictional torque that acted on the wheel to bring it to rest? Answer must be 3.46 N*m
2) A wave generator is attached to one end of a thin string of density 3.5
Explanation / Answer
wi = 1200 rpm = 1200*2*3.14/60 = 125.6 rad/s
Wf = 0
alfa = wf-wi/t = 31.4 rad/s^2
theta = (wi + wf)/2*t = 251.2 rad
theta = 251.2/2*3.14 = 40 revolutions
#b )
Torque = I*alfa = (1/2)*1.8*0.35*0.35*31.4 = 3.46185 Nm
2)
A) 4?/2 = L
? = 0.6 m
B) v = ?*f = 0.6*60 = 36 m/s
V = sqrt(T/u)
T = V^2*u = 36*36*3.5e-4 = 0.4536 N
C) T = m*g
m = 0.04628 kg