14. FIGURE Q4.14 shows four rotating wheels. For each, determine the signs $(+$or $-)$of $\omega$and $\alpha$.

As the wheel (a) is rotating in counter-clock wise direction therefore the sign of angular velocity as $\omega =-\text{\hspace{0.05em}ve}$, and since the wheel is speeding up, therefore the angular acceleration$\alpha =(+)\text{\hspace{0.05em}ve}$

As the wheel (b) is rotating in clock wise direction therefore the sign of angular velocity as$\omega =+$ , and since the wheel is slowing down, therefore the angular acceleration$\alpha =-$

As the wheel (c) is rotating in counter-clock wise direction therefore the sign of angular velocity as $\omega =-\text{ve}$, and since the wheel is slowing down, therefore the angular acceleration$\alpha =-$

As the wheel (d) is rotating in clockwise direction therefore the sign of angular velocity as $\omega =+ve$, and since the wheel is speeding up, therefore the angular acceleration $\alpha =(+)\text{\hspace{0.05em}ve}$.