A bicycle wheel is rotating at 49 rpm when the cyclist begins to pedal harder, giving the wheel a constant angular acceleration of 0.45 rad/s2. what is the wheel's angular velocity, in rpm, 9.0 s later?

In 9 sec, it increases the angular velocity by (0.45 x 9) rad/s which will give us 4.05 rad/s

Now get the angular velocity and divide it 2pi = 4.05 by 2 (pi) to give how many revolutions 4.05 rad is equivalent to = 0.6446 rps

Them, multiply this by 60 to get it from rps to rpm increase (0.6446 x 60) = 38.676 rpm

Add this and the starting revolution frequency of 49 rpm to give: (49 rpm + 38.676 rpm) = 87.6760 rpm