A hollow spherical shell has mass 8.35 kg and radius 0.225 m. It is initially at rest and then rotates about a stationary axis that lies along a diameter with a constant acceleration of 0.885 rad/s^2.

Required:
What is the kinetic energy of the shell after it has turned through 6.00 rev?

Respuesta :

Answer:

K = 9.41 J

Explanation:

The kinetic energy of a spherical shell is given as:

[tex]k = \frac{1}{2} I \omega^2[/tex]

where I = moment of inertia and

ω = angular velocity

Let us find I:

For a hollow sphere:

[tex]I = \frac{2}{3} MR^2[/tex]

where M = mass = 8.35 kg

R = radius = 0.225 m

[tex]=> I = \frac{2}{3} * 8.35 * 0.225^2 = 0.282 kgm^2[/tex]

Let us find ω:

Since angular acceleration is constant:

[tex]\omega^2 = \omega_0^2 + 2\alpha(\theta - \theta_0)\\\\\omega_0 = 0\\\\=>\omega^2 = 2\alpha(\theta - \theta_0)\\\\\theta - \theta_0 = 6 * (2 * \pi) = 37.70 rad\\\\\omega^2 = 2 * 0.885 * 37.70 = 66.729[/tex]

Therefore, its kinetic energy is:

[tex]K = \frac{1}{2} * 0.282 * 66.729\\\\K = 9.41 J[/tex]