A wheel of radius 20 cm is pushed to move on a rough horizontal...

Distance travelled by the wheel in one revolution, $s = 60 \text{ cm}$

Angle rotated by the wheel in one revolution, $\theta = 2\pi \text{ rad}$

Distance the wheel would travel if it were in pure rolling, $s_{rolling} = R\theta = 20 \times 2\pi = 40\pi \approx 125.6 \text{ cm}$

Since $s < s_{rolling}$, the average translational velocity is less than the average rotational velocity ($v < R\omega$).

The velocity of the lowest point of the wheel (point of contact) with respect to the ground is given by $v_{contact} = v - R\omega$.

Since $v < R\omega$, we get $v_{contact} < 0$. This implies that the point of contact is slipping in the backward direction, opposite to the translational motion of the wheel.

Kinetic friction always opposes the relative motion of the surfaces in contact. Since the point of contact slips backwards, the frictional force exerted by the surface on the wheel must act in the forward direction.

Therefore, the frictional force acts along the velocity of the wheel.