A cord of negligible mass is wound around the rim of a wheel supported by spokes with negligible mass. The mass of wheel is 10 kg and radius is 10 cm and it can freely rotate without any friction. Initially the wheel is at rest. If a steady pull of 20 N is applied on the cord, the angular velocity of the wheel, after the cord is unwound by 1 m, would be:

Since the wheel has negligible mass spokes, its mass is concentrated at the rim (treating it as a hoop/thin ring):

$$I = MR^2$$

$$I = 10 \text{ kg} \times (0.1 \text{ m})^2 = 0.1 \text{ kg m}^2$$

The work done by the pull (F) over the unwound distance (s) equals the change in rotational kinetic energy:

$$\text{Work} = \Delta KE_{rot}$$

$$F \cdot s = \frac{1}{2} I \omega^2$$

$$20 \times 1 = \frac{1}{2} \times 0.1 \times \omega^2$$

$$\omega = 20 \text{ rad/s}$$