<span> We're given that x=25 when t=2: </span>
<span>25 = 3 + 12(2) + (1/2)a(2)^2 </span>
<span>Thus a = -1 cm/sec^2</span>
By definition, acceleration is the change in velocity per change of time. As time passes by, the time increases in value. So, when the acceleration is decreasing while the time is increasing, then that means that the change of velocity is also decreasing with time. So, optimally, the initial velocity and the velocity at any time are very relatively close to each other,
With constant angular acceleration 
, the disk achieves an angular velocity 
at time 
according to
and angular displacement 
according to
a. So after 1.00 s, having rotated 21.0 rad, it must have undergone an acceleration of
b. Under constant acceleration, the average angular velocity is equivalent to
where 
and 
are the final and initial angular velocities, respectively. Then
c. After 1.00 s, the disk has instantaneous angular velocity
d. During the next 1.00 s, the disk will start moving with the angular velocity 
equal to the one found in part (c). Ignoring the 21.0 rad it had rotated in the first 1.00 s interval, the disk will rotate by angle according to
which would be equal to
