A large stone disk is viewed from above and is initially at rest as seen in the
ID: 1466139 • Letter: A
Question
A large stone disk is viewed from above and is initially at rest as seen in the figure below. The disk has a mass of 145.0 kg and a radius of 2.200 m. A constant force of 40.0 N is applied tangent to the edge of the disk for 62.0 s, causing the disk to spin around the z axis.
(a) Calculate the angular acceleration of the stone, finding both the direction and magnitude. (Express your answer in vector form. Substitute numeric values, do not use variables.)
rad/s2
(b) What is the final angular velocity of the stone? (Express your answer in vector form. Substitute numeric values, do not use variables.)
rad/s
(c) Calculate the translational speed for a point on the edge of the stone after 62.0 s. in
m/s
Explanation / Answer
moment of inertia = I = (1/2)*M*R^2
torque = I*alfa
F*R = I*alfa
40*2.2 = (1/2)*145*2.2^2*alfa
alfa = 0.251 rad/s^2
alfa = 0.251 k
(b)
initial velocity = wi = 0
final angular velocity = wf =wi + alfa*t
Wf = 0 + 0.251*62 = 15.562 rad/s
wf = 11.562 k
(c)
Vf = r*wf = 2.2*15.562 = 34.2364 m/s
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