Question

A flywheel of radis 2 m and mass 8 kg rofotes at an angular speed of 4 rad's about an axis perpendicular to
it through its centre. The kinetic energy of rotation is
1) 128 J 2) 196J3) 256J 4) 392 J​

Answer 1

Answer:

TAKE THE ANSWER FROM ATTATCHMENT

Answer 2

Given:

• The radius of gyration = 2 m
• The mass of a flywheel = 8 kg
• The angular velocity = 4 rad/s

To Find:

• The kinetic energy of the rotation.

Solution:

The formula to find rotational kinetic energy is given by,

⇒ K.E = [I×(ω×ω)]/2 → { equation 1}

Where "I" is the moment of inertia, and "ω" is the angular velocity.

We do not have the value of "I" with us, therefore the formula to find "I" is given by,

⇒ I = m$K^2$  → {equation 2}

Where "m" is the mass, and "K" is the radius of gyration.

Substitute the values from the given data in equation 2.

⇒ I = 8 × 4 = 32

Now substitute the value of I and ω in equation 1. We get,

⇒ K.E = [32×(4×4)]/2

⇒ K.E = 512/2

⇒ K.E = 256 J

∴ The kinetic energy of rotation = 256 J. (option 3)