Answer:
magnitude of the frictional torque is 0.11 Nm
Explanation:
Moment of inertia I = 0.33 kg⋅m2
Initial angular velocity w° = 0.69 rev/s = 2 x 3.142 x 0.69 = 4.34 rad/s
Final angular velocity w = 0 (since it stops)
Time t = 13 secs
Using w = w° + §t
Where § is angular acceleration
O = 4.34 + 13§
§ = -4.34/13 = -0.33 rad/s2
The negative sign implies it's a negative acceleration.
Frictional torque that brought it to rest must be equal to the original torque.
Torqu = I x §
T = 0.33 x 0.33 = 0.11 Nm
Answer:
The cannon ball was not able to hit the target because the target is located at a height of 50 m whereas the cannon ball was only above to get to a height of 20 m.
Explanation:
From the question given above, the following data were obtained:
Height to which the target is located = 50 m
Initial velocity (u) = 20 m/s
To know whether or not the cannon ball is able to hit the target, we shall determine the maximum height to which the cannon ball attained. This can be obtained as follow:
Initial velocity (u) = 20 m/s
Final velocity (v) = 0 (at maximum height)
Acceleration due to gravity (g) = 10 m/s²
Maximum height (h) =?
v² = u² – 2gh (since the ball is going against gravity)
0² = 20² – (2 × 10 × h)
0 = 400 – 20h
Collect like terms
0 – 400 = – 20h
– 400 = – 20h
Divide both side by – 20
h = – 400 / – 20
h = 20 m
Thus, the the maximum height to which the cannon ball attained is 20 m.
From the calculations made above, we can conclude that the cannon ball was not able to hit the target because the target is located at a height of 50 m whereas the cannon ball was only above to get to a height of 20 m.
Answer:

Explanation:
Assuming uniform spread of sound with no significant reflections or absorption. We know that sound intensity varies
where r is the distance
Since intensity is given then when at 3 m


Since we have the constant then at 4m
Intensity, 
Answer:
El resorte al comprimirse adquiere energía potencial elástica.
Explanation:
Por conservación de la energía, y si no hay agentes externos (como pérdida de energía por rozamiento), la energía cinética que proviene del movimiento de la puerta al abrirse se transfiere al resorte en forma de energía potencial elástica cuando el resorte se comprime.
En el proceso de descompresión ocurre lo contrario, es decir, la energía potencial elástica del resorte se transforma en energía cinética que es transferida a la puerta para cerrarse.
Por lo tanto, el resorte al comprimirse adquiere energía potencial elástica.
Espero que te sea de utilidad!