91Ó°ÊÓ

As the wheel (a) is rotating in counter-clock wise direction therefore the sign of angular velocity as $\mathrm{Ó\neg }=−\text{ v±ð}$, and since the wheel is speeding up, therefore the angular acceleration$\mathrm{Î\pm }=(+)\text{ v±ð}$

As the wheel (b) is rotating in clock wise direction therefore the sign of angular velocity as$\mathrm{Ó\neg }=+$ , and since the wheel is slowing down, therefore the angular acceleration$\mathrm{Î\pm }=−$

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

As the wheel (d) is rotating in clockwise direction therefore the sign of angular velocity as $\mathrm{Ó\neg }=+ve$, and since the wheel is speeding up, therefore the angular acceleration $\mathrm{Î\pm }=(+)\text{ v±ð}$.