A wheel is turning about an axis through its center with constant angular acceleration. Starting from rest, at t=0t=0, the wheel turns through 8.75 revolutions in t=t= 13.0 ss . At 13.0 ss the kinetic energy of the wheel is 36.0 J Part A For an axis through its center, what is the moment of inertia of the wheel? Express your answer with the appropriate units.

Respuesta :

Answer:

The moment of inertia is 1.01 kg m²

Explanation:

Given:

θ = 8.75 revolutions = 2π * 8.75 = 54.98 rad

t = time = 13 s

Ek = kinetic energy = 36 J

The angular acceleration is equal to:

[tex]\alpha =\frac{\theta }{0.5t^{2} } =\frac{54.98}{0.5*13^{2} } =0.65rad/s^{2}[/tex]

The angular velocity is:

w = αt = 0.65 * 13 = 8.45 rad/s

The moment of inertia is:

[tex]I=\frac{2E_{k} }{w^{2} } =\frac{2*36}{8.45^{2} } =1.01kgm^{2}[/tex]

Lanuel

The moment of inertia of the wheel for an axis through its center is equal to 1.01 [tex]kgm^2[/tex].

Given the following data:

  • Initial angular speed = 0 rev/s (since it's starting from rest).
  • Final angular displacement = 8.75 revs
  • Time = 13.0 seconds
  • Kinetic energy = 36.0 Joules

Conversion:

Final angular displacement = 8.75 revs to rad = [tex]8.75 \times 2\pi = 54.98\;rad[/tex]

To calculate the moment of inertia of the wheel for an axis through its center:

Mathematically, the final angular speed is given by this formula:

[tex]\theta_f - \theta_i = \omega_i t + \frac{1}{2} \alpha t\\\\\theta_f - \theta_i = \omega_i t + \frac{1}{2} (\omega_f -\omega_i) t\\\\\theta_f - 0 = 0t + \frac{1}{2} (\omega_f -0) t\\\\\theta_f = \frac{1}{2} \omega_f t\\\\\omega_f = \frac{ 2 \theta_f}{t}[/tex]

Substituting the given parameters into the formula, we have;

[tex]\omega_f = \frac{ 2 \times 54.98}{13.0} \\\\\omega_f = \frac{ 109.96}{13.0} \\\\\omega_f =8.46\;rad/s[/tex]

Now, we can calculate the moment of inertia of the wheel by using this formula:

[tex]K.E = \frac{1}{2} I\omega_f^2\\\\I=\frac{2K.E}{\omega_f^2} \\\\I=\frac{2 \times 36.0}{8.46^2} \\\\I=\frac{72.0}{71.57}[/tex]

Moment of inertia, I = 1.01 [tex]kgm^2[/tex]

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