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Pgeske

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In summary, if a meteor entered the Earth's atmosphere at 11 or so km/sec and impacted the Earth with a direct hit (by impact time it is 4 kg), the force of impact would be Kinetic energy, equivalent to 4 kg of TNT.

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Pgeske

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- #2

Borek

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Are you sure it is force you are interested in?

- #3

Pgeske

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Energy, force, momentum, or anything... I just need something.

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nesp

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Pgeske

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nesp

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Pgeske said:

In your OP you said by impact time it was 4kg so I assumed that was what remained after going through the atmosphere. If the 4KG is at the point of entry into the atmosphere, this is a more difficult problem. You have to take into account the angle of entry, the mass density, etc. Temperatures generated by air friction would vaporize a large amount of the meteorite and might explode it into much smaller pieces and dust, so the impact energy at ground level would have to account for the impact area, the average size of pieces, etc. It's not a problem that has an easy answer without a lot of assumptions. If this was a HW problem, maybe that's the point.

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Pgeske

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Drakkith

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nesp

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- #10

Drakkith

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What do you mean? How does 11 km/s corrospond to the force of gravity from earth?

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cjl

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- #12

Borek

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cjl said:

That's only assuming planet without atmosphere.

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cjl

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- #14

Borek

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Pgeske said:If a meteor entered the Earth's atmosphere at 11 or so km/sec

cjl said:Yes, but it is a reasonable assumption for the speed it will have at the top of the atmosphere.

I see what you are saying, but you don't need any assumption about the entry speed, as entry speed is given.

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nesp

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- #16

cjl

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Borek said:I see what you are saying, but you don't need any assumption about the entry speed, as entry speed is given.

Yes, I was responding about why 11 km/s is just about the slowest reasonable speed for a meteor.

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JohnKingtamer

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How many asteroids in a series of asteroids hitting the moon with each both slowing the moon and deflecting it increasingly toward Earth would it take to cause the moon to hit the earth? Assuming it splashed down in the Pacific, could the resulting tsunami inundate everything below 1000 feet above sea level? How far up various major rivers would that reach?

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Ryan_m_b

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JohnKingtamer said:What if a series of asteroids hit the moon with each both slowing the moon and deflecting it increasingly toward earth?

What about "what if"? What question are you asking exactly?

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Trevormbarker

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Acceleration due to gravity is 9.8 m/s^2 so ~ 40 N

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Ryan_m_b

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Trevormbarker said:

Acceleration due to gravity is 9.8 m/s^2 so ~ 40 N

Are you sure you're using F=MA correctly here? i.e. in the context of the question asked.

- #21

Trevormbarker

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ryan_m_b said:Are you sure you're using F=MA correctly here? i.e. in the context of the question asked.

I thought so, correct me if I am wrong, the thread name was how much force would a 4 Kg meteor impact Earth with. What am I doing incorrectly?

- #22

Ryan_m_b

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Trevormbarker said:I thought so, correct me if I am wrong, the thread name was how much force would a 4 Kg meteor impact Earth with. What am I doing incorrectly?

This question is possibly going to reveal to PF how simplistic some of my understanding is but here goes...

F=MA refers to the energy needed to accelerate an object of given mass i.e. how much force does it take to accelerate a 4kg object at 1g = 40N per second.

However the OP isn't "what force does a 4kg asteroid undergo when falling to Earth", it's how much energy would the 4kg asteroid release. That would be worked out by figuring out the kinetic energy of the asteroid.

For another way to see why F=MA doesn't provide an answer to the OP consider this, using it the way you have done (where A is the acceleration in the gravity field of Earth) would give the same result for a 4kg asteroid traveling at 11kmps and one traveling at 111,000kmps.

- #23

Trevormbarker

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ryan_m_b said:This question is possibly going to reveal to PF how simplistic some of my understanding is but here goes...

F=MA refers to the energy needed to accelerate an object of given mass i.e. how much force does it take to accelerate a 4kg object at 1g = 40N per second.

However the OP isn't "what force does a 4kg asteroid undergo when falling to Earth", it's how much energy would the 4kg asteroid release. That would be worked out by figuring out the kinetic energy of the asteroid.

For another way to see why F=MA doesn't provide an answer to the OP consider this, using it the way you have done (where A is the acceleration in the gravity field of Earth) would give the same result for a 4kg asteroid traveling at 11kmps and one traveling at 111,000kmps.

I see what your saying, sorry about this missunderstanding, So according to the OP should one not just use Ek = 1/2mv^2 and use different values for v depending on how fast the meteor is moving

- #24

Ryan_m_b

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Trevormbarker said:I see what your saying, sorry about this missunderstanding, So according to the OP should one not just use Ek = 1/2mv^2 and use different values for v depending on how fast the meteor is moving

The OP provided a speed for the asteroid at the surface (11kmps) which comes to 0.25GJ using http://www.csgnetwork.com/kineticenergycalc.html".

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The force of impact from a 4 kg meteor can be calculated using the formula F=ma, where F is the force, m is the mass of the meteor, and a is the acceleration due to gravity. Assuming a gravitational acceleration of 9.8 m/s^2, the force of impact would be approximately 39.2 Newtons.

The force of impact from a meteor can be affected by several factors, including the mass and velocity of the meteor, the angle of impact, and the composition of the impact surface. Additionally, air resistance and atmospheric conditions can also play a role in altering the force of impact.

The force of a 4 kg meteor would be relatively low compared to larger objects, such as asteroids or comets, which can range in mass from several tons to kilometers in diameter. However, it would still be significant enough to cause damage upon impact, depending on the velocity and angle of impact.

Yes, the force of impact from a 4 kg meteor can be predicted using mathematical models and simulations. Scientists use data on the mass, velocity, and trajectory of the meteor to estimate the force and potential effects of impact on the earth's surface.

There are several strategies for mitigating the force of impact from a meteor, including early detection and tracking, deflection techniques, and impact avoidance planning. These strategies are continuously being researched and developed by scientists and organizations such as NASA to better prepare for potential meteor impacts in the future.

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