26 points

Thats inefficient, you dont need to cancel the angular momentum as there was no time limit on how long it takes rhe child to enter the sun and there also was not a specified required trajectory. The child can just spiral into the sun

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3 points

I don’t think you can achieve a spiral orbit in an area with so little friction, mostly devoid of dust and gas, else the earth would be on one of those too…

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21 points

There are no spiral orbits. Canceling the forward motion is exactly what you need to do, to bring down the next periapsis to 0. Now, you can go with a periapsis of about half a million km, because the sun is pretty big, but that is not a significant difference. Getting anywhere near the sun, is the hard part.

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3 points

It’s much more efficient in this case to do a bi-elliptic transfer: raise apoapsis very far out, then lower your periapsis once you are at apoapsis. Wikipedia says you could do it with about 8.8 km/s delta v. Versus 24 or so for a basic Hohman transfer (still a bit better than 30)

Sadly the bi-elliptic transfer requires two burns so you can’t do it with a kick.

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11 points

Right, I wanted to ask: is that actually the minimum energy to make the child reach the sun? What’s the minimum energy to launch something so it reaches the sun?

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1 point
*

The speed will be related to escape speed of sun. Based on https://en.m.wikipedia.org/wiki/Escape_velocity It will be Vte which is 16.6 km/s (or Ve 42.1). So when object at earth orbit and has lower speed than 16.6 it can’t keep the orbit and will slowly fall into sun.

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16 points

The minimum would be something like punting your kid to the orbit of Venus for a gravity assist that takes it to one of the outer planets where another gravity assist can push it to the edge of the solar system.
Out there, the angular momentum of the orbiting child will be very low and can be canceled out by a small thrust.
The child will then fall back into the sun. But this requires remote controlled thrusters strapped to the child. And a life support system if you want your child to actually die by burning in the sun. And then, the child will be well into their teens by the time they reach it.

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6 points

Give them time to think about what they did, maybe learn from it

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4 points

Just tell them to give a small poot on their tenth birthday it’s all good

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4 points

Right, and what force is acting on the child to make it deviate from a circular orbit into a spiral one?

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2 points

You could use a gravity assist from another planet

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25 points
*

Faster than the speed of light.

Lol that is some shit maths for a checks note astrophysics major i am shit at maths and even i know its wrong.

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-1 points
Deleted by creator
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15 points

The reliable way to get an answer from the internet is to provide the wrong answer, then someone will come and correct you, providing the answer you seek. (Xkcd, probably maybe?)

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7 points

This is a proven fact. Expose yourself early and often, that’s my motto.

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5 points
*

Im not allowed within 500m of the supermarket after i exposed myself last time.

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16 points
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Are you arguing that 1.12 billion m/s is NOT faster than the speed of light, or are you arguing that the speed required by the kick is not 1.12 billion m/s? Because if it’s the former, the speed of light in a vacuum is 300 million m/s (to 3 significant figures), or less than one third of that kick speed. If you’re arguing the latter, I don’t feel like checking all of the calculations this early in the morning, but you are probably right on that point.

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3 points

Velocity addition and conservation of momentum don’t work like that if the speeds are close to the speed of light.

For further details, please check out special relativity theory.

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24 points

Cut the extra inch off the long side to get a 4" square, then cut the remaining 1" x 4" piece into 4 1" squares. The boy never said the squares had to be the same size.

If the triangles have already been cut, it’s a peanut butter sandwich: use peanut butter on the edges to glue it back together and cut the squares. The child gave you a challenge, think outside the box!

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6 points

If the triangles have already been cut, the kid gets a brand new sandwich fully intact, crust and all, and a knife. Let’s see you cut this sandwich better than I can brayxtyn

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8 points

If that’s the child’s name, you have no one to blame but yourself, and are probably underqualified for handling a butter knife.

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4 points

I’m partial to Brexit for my first childs name.

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33 points
*

i’d cut squares out of the triangles.

Once the kid realizes he’s getting less because of his demands, he might change his mind about shape being important.

Edit: or make him do it. toss in a lesson about geometry, too.

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4 points

Parent’s already thinking outside the biosphere.

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29 points

Or just get another child. I know they don’t grow on trees but I’m sure they grow somewhere

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17 points

The fiery pits of hell

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13 points

That not a nice name for the uterus

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8 points

But still accurate. That fucker tries to kill me every few weeks for some reason.

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72 points
*

If your leg has a mass of 2kg, 1.1×10^10 J of kinetic energy would require your leg to be moving at about 150 100 km/second not faster than the speed of light.

TLDR: Their math is shit.

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2 points

Yeah, their answer just intuitively seems very wrong. The ratio between the kid’s weight and your foot’s weight should be equal to the ratio between their final speed and your foot’s required speed. Ridiculous.

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11 points

Besides, if you really needed those kinds of speed, you’d obviously have to calculate with relativistic formulas. Energy is asymptotical at the speed of light.

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1 point
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100 km/sec is not relativistic and even if it were, at no point would that object need to or could exceed the speed of light. Its a fundamental limit that cant be broken.

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2 points

Yeah, I was refering to the OP’s calculated result in that it’s incorrect not only by incorrect math, but also incorrect physics.

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3 points

Setting aside the correctness in OP for the moment, what’s being said here is that you don’t actually need to break lightspeed. The foot would have to be moving asymptomaticly close to lightspeed, but not passing it. OP used an equasion that works classically, but we’re in territory where that model breaks down.

But if the math doesn’t work out that way, anyway, then whatever, classical equasions are fine.

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16 points

Pretty sure you’re generating twice as much energy as needed, the required speed is only about 106km/s

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2 points
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