Question

A solid cylinder of mass 2 kg and radius 20cm is rotating about its axis with a frequency of 10 Hz. What is the rotational kinetic energy of the cylinder

Answer 1

Answer on Question #41137, Physics, Mechanics | Kinematics | Dynamics

Question:

A solid cylinder of mass 2 kg and radius 20cm is rotating about its axis with a frequency of 10 Hz. What is the rotational kinetic energy of the cylinder?

Answer:

Rotational kinetic energy equals:

$$T = \frac {I \omega^ {2}}{2}$$

where $I$ is moment of inertia, $\omega$ is angular speed.

Moment of inertia for cylinder equals:

$$I = m r ^ {2}$$

where $m$ is mass, $r$ is radius.

Angular speed equals (one revolution is equal to $2\pi$ radians):

$$\omega = 2 \pi f$$

where $f$ is frequency.

Therefore:

$$T = \frac {m r ^ {2}}{2} (2 \pi f) ^ {2} = 158 \, J$$

Answer: 158 J

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