A student is standing 8 m from a roaring truck engine that is measured at 20. The student moves 4 m closer to the engine. What i
2 answers:
By knowing how intensity relates to distance, we will see that at 4 meters of the engine the intensity is 80.
<h3>How sound intensity relates to distance?</h3>
The sound spreads in a solid angle like all waves, so the intensity of the sound will decrease with the distance squared, this means that:
Where P is the sound power, we know that when the student is at 8m from the engine, the intensity measured is 20 (it does not tell the units) so we have:
Now, if you move 4 meters closer to the engine, your new position will be:
r = 4m
Then we have:
If you want to learn more about sound intensity, you can read:
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Answer:
41°
Explanation:
Kinetic energy at bottom = potential energy at top
½ mv² = mgh
½ v² = gh
h = v²/(2g)
h = (2.4 m/s)² / (2 × 9.8 m/s²)
h = 0.294 m
The pendulum rises to a height of above the bottom. To determine the angle, we need to use trigonometry (see attached diagram).
L − h = L cos θ
cos θ = (L − h) / L
cos θ = (1.2 − 0.294) / 1.2
θ = 41.0°
Rounded to two significant figures, the pendulum makes a maximum angle of 41° with the vertical.
