PDA

View Full Version : meteors, their speed



north
2007-Sep-03, 06:38 AM
if meteors are of the size of grains of sand , how is it that they can contain enough energy to travel at , if I remember right , 30,000 miles per/hr.

is not the speed of a mass related too its ability to absorb energy? so that the smaller the object is the less speed it is able to reach , because the energy supplied overwhelms the ability of the mass to absorb this energy.

cjl
2007-Sep-03, 06:43 AM
Not at all. Any size object can travel at any sublight speed, and if anything, the smaller an object, the less energy required to accelerate it to very high velocity.

A good example of this is that individual particles can be accelerated very close to the speed of light in particle accelerators, despite the fact that they are much smaller than anything that could be called a meteorite.

Don't think of it as the meteor "containing" the energy, think of the energy as being converted into the speed at which the meteor travels, without the meteor containing anything.

north
2007-Sep-03, 07:00 AM
Not at all. Any size object can travel at any sublight speed, and if anything, the smaller an object, the less energy required to accelerate it to very high velocity.

A good example of this is that individual particles can be accelerated very close to the speed of light in particle accelerators, despite the fact that they are much smaller than anything that could be called a meteorite.

[QUOTE=cjl;1063307] Don't think of it as the meteor "containing" the energy, think of the energy as being converted into the speed at which the meteor travels, without the meteor containing anything.

but how does the meteor get to this travel speed in the first place? I mean wouldn't , once the particle leaves its home source , so to speak , slow down ?

in an accelerator the particle is PUSHED by a constant magnetic field .

meaning is the meteorite and a particle in an accelerator a fair comparison?

AGN Fuel
2007-Sep-03, 07:20 AM
The velocity of the dust particle will generally be governed by the orbital mechanics of the protoplanetary disc from which the solar system contracted, and any gravitational interactions with planets etc in the intervening 4.5 billion years! (Depending on the source of the dust: if it was "outcast" by the outgassing of a comet, then obviously it will be dependent on orbital mechanics of the comet and the specifics of the outgassing).

Don't forget that you are talking about relative velocities as well. The Earth is in orbit around the sun with a tangential velocity of about 30 km/s (which equates to about 67,500 mph if my working out is correct).

Therefore, the dust particle could be moving in a similar orbit to the Earth with a tangential velocity of 37,500 mph (not unreasonable for a decaying orbit or for cometary detritus) and it will still be 'swept' up by the Earth with an impact velocity of your 30,000mph!


but how does the meteor get to this travel speed in the first place? I mean wouldn't , once the particle leaves its home source , so to speak , slow down ?

Why? Read up on Newton's first law.

astromark
2007-Sep-03, 08:20 AM
North; you ask about a small particle loosing its velocity. Why do you think it would do that? Space is empty. There is no friction. Very little likelihood of a collision. There is no reason your particle will slowdown.
Nothing in space is still. As described by 'AGN fuel'. This planet is moving on its orbital velocity around the Sun. Which is itself orbiting the central mass of this galaxy. Which is itself going that way quiet quickly...:) Your little particle of 'dust' could be doing 70,000 km/hr. without any need for propulsion.
Your small particle does not contain the energy of its velocity. That velocity is entirely dependent on what ever accelerated it in the first place. There is kinetic energy but, that is not so much stored but a resultant by product of the mass under motion. The small mass of this particle does not inhibit its velocity.