You have a grindstone (a disk) that is 90.0 kg, has a 0.340-m radius, and is turning at 90.0 rpm, and you press a steel axe against it with a radial force of 20.0 N. (a) Assuming the kinetic coefficient of friction between steel and stone is 0.20, calculate the angular acceleration of the grindstone. (

Respuesta :

Answer:

Explanation:

Given mass of grindstone [tex]m=90\ kg[/tex]

radius of stone [tex]r=0.34\ m[/tex]

angular speed of disc [tex]\omega =90\ rpm[/tex]

Steel Axle applying a force of [tex]F=20\ N[/tex]

coefficient of kinetic friction [tex]\mu =0.2[/tex]

Frictional Torque applied by steel is given by

[tex]\tau=r\times f_r[/tex]

[tex]\tau =r\times \mu F[/tex]

where [tex]f_r[/tex]=frictional force

[tex]\tau =r\times \mu \times F[/tex]

[tex]\tau =0.34\times 0.2\times 20[/tex]

[tex]\tau =1.36\ N-m[/tex]

Torque is also given by

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

where [tex]\alpha [/tex]=angular acceleration

I=moment of Inertia

[tex]\tau =0.5Mr^2\times \alpha [/tex]

[tex]0.5Mr^2\times \alpha =1.36\ N-m[/tex]

[tex]0.5\times 90\times 0.34^2\times \alpha =1.36[/tex]

[tex]\alpha =0.261\ rad/s^2[/tex]