Answer:
<em>155.80rad/s</em>
Explanation:
Using the equation of motion to find the angular acceleration:

is the final angular velocity in rad/s
is the initial angular velocity in rad/s
is the angular acceleration
t is the time taken
Given the following

Time = 4.1secs
Convert the angular velocity to rad/s
1rpm = 0.10472rad/s
6100rpm = x
x = 6100 * 0.10472
x = 638.792rad/s
Get the angular acceleration:
Recall that:

638.792 = 0 + ∝(4.1)
4.1∝ = 638.792
∝ = 638.792/4.1
∝ = 155.80rad/s
<em>Hence the angular acceleration as the blades slow down is 155.80rad/s</em>
P = density × gravity acceleration × height
P = 1200 × 9.81 × 15/100
P = 1765.8
Solution :
The motion in the y direction.
The time taken by the toy rocket to hit the ground,

S = distance travelled = 30 m
u = 0 m/s
a = 
t= time in seconds
Therefore, 
t = 2.47 sec
Now motion in the x direction,
u = 12 m/sec

Upon integration 'v' with respect to 't'

Once again integrating with respect to t,


= 0.0176+29.64
= 29.65 m
Therefore, the toy rocket will hit the ground at 29.65 m from the building.
Power = 
Delilah: 170J/30s = 5.66 W
Adam: 260J/20s = 13 W