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Examples in Chapter 9 . 9.25. A flywheel with a radius of 0.3 m starts from rest and accelerates with a constant angular acceleration of 0.6 rad/s 2 . Compute the magnitude of the angular accleration the radial acceleration The resultant acceleration of a point on its rim At the start I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
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Presentation Transcript ### Examples in Chapter 9 9.25
• A flywheel with a radius of 0.3 m starts from rest and accelerates with a constant angular acceleration of 0.6 rad/s2 . Compute the magnitude of
• the angular accleration
• the radial acceleration
• The resultant acceleration of a point on its rim
• At the start
• After it has turned through 600
• After it has turned through 1200 Starting conditions
• a = 0.3 rad/s
• w0 =0
• r= 0.3 m     9.46
• A light flexible rope is wrapped several times around a hollow cylinder with a weight of 40 N and a radius of 0.25 m that rotates without friction about a fixed horizontal axis. The cylinder is attached is attached to the axle by spokes of a negligible moment of inertia. The cylinder is initially at rest. The free end of the rope is pulled with a constant force P for a distance of 5 m at which the end of the rope is moving at 6 m/s. If the rope does not slip on the cylinder, what is the value of P? Some figurin’
• W=DR
• Where R= ½ I w2
• v=rw or v/r=w
• Initially, w0 =0 so DR= ½ I (v/r)2
• From I=m*r2=(40 N/9.8)*(.25)2=0.255
• W=F*d or P*(5 m)
• W=5P
• P= (1/2)*0.255*(6/.25)2/5=14.7 N 9.71
• A vacuum cleaner belt is looped over a shaft of radius 0.45 cm and a wheel of radius 2.0 cm . The arrangement is shown below. The motor turns the shaft at 60 rev/s and the shaft is connected to a beater bar which sweeps the carpet. Assume that the belt doesn’t slip.
• What is the speed of a point on the belt?
• What is the angular velocity of the belt? Some more figurin’
• Part a) v=r*w where
• r=0.45 cm
• w= 60 rev/s *(2*p radians/rev)=377 rad/s
• v=0.45*377=169 cm/s or 1.69 m/s
• Part b) w2= 169 cm/s / 2 cm =84.8 rad/s Hint on 9.72
• The wheels are coupled so that there is the tangential velocity is constant so that

w1/w2 = r2/r1