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A 220 g , 23-cm-diameter plastic disk is spun on an axle through its center by an electric motor.What torque must the motor supply to take the disk from 0 to 1800 rpm in 4.6 s ?

Respuesta :

Answer:

The torque applied on the plastic disk is 40.97 N-m.

Explanation:

Given that,

Mass of the disc, m = 220 g = 0.22 kg

Diameter of the disk, d = 23 cm

Radius, r = 11.5 cm = 0.115 m

Initial speed of the disk, [tex]\omega_o=0[/tex]

Final speed of the disk, [tex]\omega_f=1800\ rpm=188.49\ rad/s[/tex]

Time, t = 4.6 s

The relation between torque and angular acceleration is given by :

[tex]\tau=I\alpha[/tex]

I is the moment of inertia of the disk

[tex]\tau=I\alpha[/tex]

[tex]\tau=\dfrac{mr^2}{2}\times \dfrac{\omega_f}{t}[/tex]

[tex]\tau=\dfrac{0.22\times (0.115)^2}{2}\times \dfrac{188.49}{4.6}[/tex]

[tex]\tau=40.97\ N-m[/tex]

So, the torque applied on the plastic disk is 40.97 N-m. Hence, this is the required solution.