A 210-kg merry-go-round in the shape of a uniform, solid, horizontal disk of radius 1.50 m is set in motion by wrapping a rope about the rim of the disk and pulling on the rope. What constant force would have to be exerted on the rope to bring the merry-go-round from rest to an angular speed of 0.600 rev/s in 2.00 s

Respuesta :

Answer:

The value of the constant force is [tex]\bf{296.88~N}[/tex].

Explanation:

Given:

Mass of the merry-go-round, [tex]m = 210~Kg[/tex]

Radius of the horizontal disk, [tex]r = 1.5~m[/tex]

Time required, [tex]t = 2.00~s[/tex]

Angular speed, [tex]\omega = 0.600~rev/s[/tex]

Torque on an object is given by

[tex]\tau = F.r = I.\alpha~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(1)[/tex]

where [tex]I[/tex] is the moment of inertia of the object, [tex]\alpha[/tex] is the  angular acceleration and [tex]F[/tex] is the force on the disk.

The moment of inertia of the horizontal disk is given by

[tex]I = \dfrac{1}{2}mr^{2}[/tex]

and the angular acceleration is given by

[tex]\alpha = \dfrac{2\pi \omega}{t}[/tex]

Substituting all these values in equation (1), we have

[tex]F &=& \dfrac{I\alpha}{r}\\&=& \dfrac{\pi m r \omega}{t}\\&=& \dfarc{\pi(210~Kg)(1.5~m)(0.600~rev/s)}{2.00~s}\\&=& 296.88~N[/tex]