Air Molecules at Mach 1: Understanding Collisions and Net Velocity

In summary, the conversation discusses the movement of molecules at sound speed and at Mach 1. There is a question about whether there are less collisions when molecules are accelerated at Mach 1, and a clarification is made that the equator has winds at Mach 1.4 due to the rotation of the Earth. The conversation also touches on the meaning of this speed and how it affects air flow, shock waves, and other phenomena. Finally, there is a mention of the average speed of air molecules and their net velocity.
  • #1
scumhearted
12
0
If molecules generally move at sound speed, given they are accelerated at Mach 1, does this mean there are less arbitrary collisions? or less collisions in general and more molecules move in the direction of mach 1 speed??
 
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  • #2
scumhearted said:
in the direction of mach 1 speed??

Let me just tell you that this phrase means nothing. Speed isn't velocity.
 
  • #3
At the equator the air moves at mach 1.4 due to the rotation of the earth. What is your question again?
 
  • #4
0xDEADBEEF said:
At the equator the air moves at mach 1.4 due to the rotation of the earth.

Well, wrt the centre of the Earth. :wink:
 
  • #5
0xDEADBEEF said:
At the equator the air moves at mach 1.4 due to the rotation of the earth. What is your question again?

This sounds like you are saying that at the equator, there are 1000 mph winds. Really?
 
  • #6
phinds said:
This sounds like you are saying that at the equator, there are 1000 mph winds. Really?

I think they're saying the air molecules move at 1000 mph wrt the centre of the Earth, not the surface.
 
  • #7
Whovian said:
I think they're saying the air molecules move at 1000 mph wrt the centre of the Earth, not the surface.

Ah ... got it. Seems meaningless. EVERYTHING moves at that speed on that basis.
 
  • #8
scumhearted said:
If molecules generally move at sound speed, given they are accelerated at Mach 1, does this mean there are less arbitrary collisions? or less collisions in general and more molecules move in the direction of mach 1 speed??

The air will have more collisions as the compression wave passes through, since the air is compressed.
 
  • #9
The point is that you ask what happens when air moves at that speed, which is probably not what you want to know. Maybe you want to know what happens in a supersonic shock wave, or in an explosion, or when you have supersonic flow around objects or ...

What happens at the speed of sound isn't really a good question.

Oh and to pick up on Whovian: with respect to the sun its mach 88 :)
 
  • #10
The average speed of air molecules is well above the speed of sound, about 1750 kph versus 1235 kph., but the net velocity is zero (in a no wind condtion) since the molecules are mostly bouncing around with no net movement. In the outer edges of the atmosphere, a very small percentage of hydrogen atoms achieve escape velocity.
 

What is mach 1 speed?

Mach 1 speed is the speed of an object moving at the same speed as sound waves in the surrounding air. In dry air at 20 °C (68 °F), the speed of sound is approximately 343 meters per second, or 1,125 feet per second, or 768 miles per hour.

How do air molecules behave at mach 1 speed?

At mach 1 speed, air molecules are compressed and move in a wave-like pattern, creating a shock wave. This shock wave causes a sudden increase in pressure and temperature, which can be damaging to structures and vehicles.

What happens to the air molecules as an object reaches mach 1 speed?

As an object reaches mach 1 speed, the air molecules in front of it are compressed and pushed together, creating a high-pressure area. Behind the object, the air molecules are spread apart, creating a low-pressure area. This creates a shock wave, which can be seen as a vapor cone around the object.

Can any object travel at mach 1 speed?

Any object can travel at mach 1 speed as long as it is able to overcome the drag forces and reach the necessary speed. However, most objects are not designed to withstand the heat and pressure generated at mach 1 speeds and would be damaged or destroyed.

What are the potential hazards of traveling at mach 1 speed?

Traveling at mach 1 speed can create high levels of heat and pressure, which can damage structures and vehicles. It can also cause a loud sonic boom, which can be harmful to people and animals. Additionally, objects traveling at mach 1 speed may experience unstable flight and difficulty maneuvering due to the shock wave created by the compression of air molecules.

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