Angular velocity is defined as the change in angular displacement divided by the change in time. In this case, the initial angle is 0.45 radians, the final angle is 0.75 radians, and the time taken is 2.0 seconds.
Angular displacement = final angle - initial angle = 0.75 radians - 0.45 radians = 0.3 radians
Angular velocity = angular displacement / time = 0.3 radians / 2.0 seconds = 0.15 radians/second
Therefore, the wheel's angular velocity is 0.15 radians/second.