# Rocket travels into space, emits sound - intensity/time question

• fuzzy361
In summary, a rocket with an initial velocity of 0 m/s travels upwards with an acceleration of 56.7 m/s2. When the rocket reaches a height of 722 m, it emits a sound that eventually reaches a ground-based monitoring station directly below. The sound is emitted uniformly in all directions and is measured at an intensity of I. Later, the station measures an intensity one-third I. With the speed of sound being 343 m/s, the elapsed time between the two measurements can be calculated by first finding the distance (r2) at which the sound intensity is one-third I, then using the speed of sound to determine the time it took for the sound to travel from the rocket to the monitoring station. The time
fuzzy361
Rocket travels into space, emits sound -- intensity/time question

## Homework Statement

A rocket, starting from rest, travels straight up with an acceleration of 56.7 m/s2. When the rocket is at a height of 722 m, it produces a sound that eventually reaches a ground-based monitoring station directly below. The sound is emitted uniformly in all directions. The monitoring station measures a sound intensity I. Later, the station measures an intensity one-third I. Assuming that the speed of sound is 343 m/s, find the time that has elapsed between the two measurements.

I= P/A
I=P/(4*pi*r^2)

## The Attempt at a Solution

I think I'm completely screwed up in the way I'm viewing this problem (by the way, I'm possibly the worst physics student ever, so please excuse the idiocy of my question). I've been assuming that 722 = r1, so I have to solve for r2 then use that, subtract r1 and use the acceleration and the displacement to find the time elapsed. After looking online and seeing how others attacked this problem, I'm just confused. Could someone explain the actual concept to me?

Figuring out how long it takes for the rocket to get from r1 to r2 only tells you the time between the *emission* of the two sound wavefronts. To get the time between their *reception*, you must also take into account the travel time of the waves.

welcome to pf!

hi fuzzy361! welcome to pf!

(try using the X2 button just above the Reply box )
fuzzy361 said:
… I've been assuming that 722 = r1, so I have to solve for r2 then use that, subtract r1 and use the acceleration and the displacement to find the time elapsed.

essentially, that's correct!

use the sound intensity to find r2

then use the speed of sound to find the time it was at r2 (obviously, a bit before the sound was actually heard )

then use that time, the acceleration, and the speed at 722 m (which you'll need to calculate first) to find the distance above 722 m

show us what you get

(but i won't see it, I'm off to bed now :zzz:)​

## 1. How does a rocket travel into space?

A rocket travels into space by using powerful engines that create enough thrust to overcome the force of gravity and lift the rocket into the Earth's atmosphere. Once in space, the rocket continues to use its engines to propel itself forward and reach its desired destination.

## 2. Why does a rocket emit sound during launch?

A rocket emits sound during launch due to the intense vibrations and pressure changes caused by the powerful engines. These vibrations create sound waves that can be heard as the rocket moves through the atmosphere. The sound may also be amplified by the shape of the rocket and its surroundings.

## 3. How does the intensity of sound change as a rocket travels into space?

The intensity of sound decreases as a rocket travels into space. This is because sound waves need a medium (such as air) to travel through, and as the rocket moves higher and higher, the air becomes thinner and can no longer support the transmission of sound.

## 4. Does the intensity of sound emitted by a rocket change over time?

Yes, the intensity of sound emitted by a rocket changes over time. As the rocket gains altitude and moves farther away from the observer, the intensity of sound decreases due to the inverse square law. This means that the sound energy is spread out over a larger area, resulting in a decrease in intensity.

## 5. How is the sound intensity of a rocket launch measured?

The sound intensity of a rocket launch can be measured using a decibel (dB) scale. This scale measures the loudness of sound and is based on a logarithmic scale. A sound level meter is typically used to measure the intensity of sound emitted by a rocket launch and can provide a reading in decibels.

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