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A 432 kg merry-go-round in the shape of a horizontal disk with a radius of 2.3 m is set in motion by wrapping a rope about the rim of the disk and pulling on the rope. How large a torque would have to be exerted to bring the merry-go-round from rest to an angular speed of 3.1 rad/s in 2.1 s

Respuesta :

Answer:

τ = 1679.68Nm

Explanation:

In order to calculate the required torque you first take into account the following formula:

[tex]\tau=I\alpha[/tex]           (1)

τ: torque

I: moment of inertia of the merry-go-round

α: angular acceleration

Next, you use the following formulas for the calculation of the angular acceleration and the moment of inertia:

[tex]\omega=\omega_o+\alpha t[/tex]         (2)

[tex]I=\frac{1}{2}MR^2[/tex]           (3)       (it is considered that the merry-go-round is a disk)

w: final angular speed = 3.1 rad/s

wo: initial angular speed = 0 rad/s

M: mass of the merry-go-round = 432 kg

R: radius of the merry-go-round = 2.3m

You solve the equation (2) for α. Furthermore you calculate the moment of inertia:

[tex]\alpha=\frac{\omega}{t}=\frac{3.1rad/s}{2.1s}=1.47\frac{rad}{s^2}\\\\I=\frac{1}{2}(432kg)(2.3)^2=1142.64kg\frac{m}{s}[/tex]

Finally, you replace the values of the moment of inertia and angular acceleration in the equation (1):

[tex]\tau=(1142.64kgm/s)(1.47rad/s^2)=1679.68Nm[/tex]

The required torque is 1679.68Nm