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The general idea behind this is as follows. After a certain size of impact, there isn't really much that will increase the devastation. So if you take two rocks, each half the size of the first, and toss it, you will quite likely have 2 large impacts, instead of 1 large impact.

If you manage to make all of the pieces small enough, then there would be less overall devastation than a single large impact, because small bits will burn up. If every piece was, say, smaller than 10m in diameter, no pieces would survive the Earth's atmosphere. Of course, that much dust in the atmosphere would cause a "nuclear winter", but that's another issue entirely. Likely that would happen no matter what occurred, although it might be somewhat worse for the large amounts of dust.

So the question then becomes, at what size is a chunk of rock harmless, and at what size does it not significantly matter what size it is? Using this handy calculator, I've played around with that. I'm going to assume you either have 1 200m rock, or 8 100m rocks widely spread. The 100m rocks produce an explosion of 22.7 Mtons, and a 1.2 km crater. The 200m rock provides a 182 MTon blast, with a crater of 3 km in diameter. The total energy is slightly larger for the 100m rocks, and the crater area is slightly larger as well. In addition, with 8 hits instead of just 1 you are more likely to be in a populated area. A 400m rock would produce an explosion of about 1.45 GTon, with a crater of about 5 km, which is also less damage than 8 200m rocks would cause. Overall, more damage comes from small rocks than larger rocks of the equivalent size, unless you can make the rocks small enough to not hit the Earth at all.

The general idea behind this is as follows. After a certain size of impact, there isn't really much that will increase the devastation. So if you take two rocks, each half the size of the first, and toss it, you will quite likely have 2 large impacts, instead of 1 large impact.

If you manage to make all of the pieces small enough, then there would be less overall devastation than a single large impact, because small bits will burn up. If every piece was, say, smaller than 10m in diameter, no pieces would survive the Earth's atmosphere.

So the question then becomes, at what size is a chunk of rock harmless, and at what size does it not significantly matter what size it is? Using this handy calculator, I've played around with that. I'm going to assume you either have 1 200m rock, or 8 100m rocks widely spread. The 100m rocks produce an explosion of 22.7 Mtons, and a 1.2 km crater. The 200m rock provides a 182 MTon blast, with a crater of 3 km in diameter. The total energy is slightly larger for the 100m rocks, and the crater area is slightly larger as well. In addition, with 8 hits instead of just 1 you are more likely to be in a populated area. A 400m rock would produce an explosion of about 1.45 GTon, with a crater of about 5 km, which is also less damage than 8 200m rocks would cause. Overall, more damage comes from small rocks than larger rocks of the equivalent size, unless you can make the rocks small enough to not hit the Earth at all.

The general idea behind this is as follows. After a certain size of impact, there isn't really much that will increase the devastation. So if you take two rocks, each half the size of the first, and toss it, you will quite likely have 2 large impacts, instead of 1 large impact.

If you manage to make all of the pieces small enough, then there would be less overall devastation than a single large impact, because small bits will burn up. If every piece was, say, smaller than 10m in diameter, no pieces would survive the Earth's atmosphere. Of course, that much dust in the atmosphere would cause a "nuclear winter", but that's another issue entirely. Likely that would happen no matter what occurred, although it might be somewhat worse for the large amounts of dust.

So the question then becomes, at what size is a chunk of rock harmless, and at what size does it not significantly matter what size it is? Using this handy calculator, I've played around with that. I'm going to assume you either have 1 200m rock, or 8 100m rocks widely spread. The 100m rocks produce an explosion of 22.7 Mtons, and a 1.2 km crater. The 200m rock provides a 182 MTon blast, with a crater of 3 km in diameter. The total energy is slightly larger for the 100m rocks, and the crater area is slightly larger as well. In addition, with 8 hits instead of just 1 you are more likely to be in a populated area. A 400m rock would produce an explosion of about 1.45 GTon, with a crater of about 5 km, which is also less damage than 8 200m rocks would cause. Overall, more damage comes from small rocks than larger rocks of the equivalent size, unless you can make the rocks small enough to not hit the Earth at all.

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The general idea behind this is as follows. After a certain size of impact, there isn't really much that will increase the devastation. So if you take two rocks, each half the size of the first, and toss it, you will quite likely have 2 large impacts, instead of 1 large impact.

If you manage to make all of the pieces small enough, then there would be less overall devastation than a single large impact, because small bits will burn up. If every piece was, say, smaller than 10m in diameter, no pieces would survive the Earth's atmosphere.

So the question then becomes, at what size is a chunk of rock harmless, and at what size does it not significantly matter what size it is? Using this handy calculator, I've played around with that. I'm going to assume you either have 1 200m rock, or 8 100m rocks widely spread. The 100m rocks produce an explosion of 22.7 Mtons, and a 1.2 km crater. The 200m rock provides a 182 MTon blast, with a crater of 3 km in diameter. The total energy is slightly larger for the 100m rocks, and the crater area is slightly larger as well. In addition, with 8 hits instead of just 1 you are more likely to be in a populated area. A 400m rock would produce an explosion of about 1.45 GTon, with a crater of about 5 km, which is also less damage than 8 200m rocks would cause. Overall, more damage comes from small rocks than larger rocks of the equivalent size, unless you can make the rocks small enough to not hit the Earth at all.