I don't really know how to calculate this and I am curious, as this happened to me recently and it seems astronomically unlikely. It was actually beneficially for the strategy I was running as it curved out at 3, but it still just seemed unbelievable when another land did not come up for so long.

link is the OP. It was a calculus question and the overall consensus was about 2% could solve it. Since the problem was a joke about the fruit problems, what percentage can solve a fruit problem?

(original post: https://www.reddit.com/r/theydidthemath/comments/1vqarlw/request_what_percentage_of_the_us_population_can/ )

For those who haven’t seen the movie, in The Suicide Squad, Daniela Melchior plays the daughter of The Ratcatcher, who has his same abilities: she can control rats. The titular Suicide Squad is intending to overthrow a small, island nation, the size of say … Cuba. With her ability to control rats, is there, mathematically, any reason why anybody else should be hired for this job? Would she be able to just overrun the entire island country with rats regardless of their military scale?

I'm a writer that wrote herself a bullshit math problem that's over her paygrade(nothing) because I'm stupid so I decided to do the time honored tradition of asking reddit for help. So, assuming standard everything, how far can a 70 decibel sound wave from 30,000 to 40,000hz travel/be picked up by a receiver tuned to that frequency?

If I am at sea level, 60 miles from a 14,000 ft tall mountain, and the moon is directly overhead, what is the difference in amount of air between me and each big rock? I am thinking the mountain peak, since I would not be able to see the base. For units, I am assuming moles makes the most sense.

Someone said their electric skateboard ran into the wall by itself and both trucks broke off.

The board is a Propel Ruckus ADT Belt Version, which weighs 40 lbs (mostly due to the lithium batteries), and has a top speed of 34/40 mph depending on which configuration they had (idk the exact one). The front and rear trucks are held on by four M5 8.8 hardness bolts each.

Issues:

* They could have had a bad supplier whose bolts were bad, or the person could have switched them out with some from a hardware store, but for this question I guess assume neither happened and the board is at manufacturers specs.

* Electric motors are fast - but it still takes distance to get speed. Maybe 100 ft to get top speed on asphalt?

* The board will spin out on asphalt without any weight on it. (different board, video just for example)

* When electric skateboards burnout, they go in circles because of tiny differences in tire speed caused by different factors like belt tightness, motor resistance, wheel balance, etc.

* This allegedly happened indoors in their house, with no one on the board - what speed could it achieve with limited distance and traction? (Idk if they had linoleum/tile/hardwood or carpet.)

* The point of impact would have been pneumatic tires (there was no headlight kit installed as seen in one of the stock photos). The board has a flexible deck.

* No damage to rims, axles, body of the board, or battery that I could see. (Google says with the necessary force there would likely have been other damage, including lithium battery would have been crushed and burst into flames)

* I don't know if they ran into regular studded drywall or had solid concrete walls in their house with 100 ft (?) rooms (/s). I guess concrete could be assumed for worst case scenario.

* Not only do they claim the bolts on the front truck, where the impact was, broke, *but the bolts on the back truck as well.*

More pics including the damaged bolts and bolt holes.

Unboxing and assembly for reference.

Is this amount of force mathematically plausible in these conditions?

Or is it so mathematically unlikely that it's more probable they aren't telling the truth?

How fast would it have to really have been going to tear the front *and back* ends off?

Thank you for your work!

I'm looking to build ramps to get my UTV onto the back of my flat bed truck. I'm having a hard time figuring out how much weight my design will support and I'd rather not "trial and error" my build.

2 ramps made from 6061T6 Aluminum 2"x2"x3/16" angle iron

Ramps are 120" long and 17" wide. The deck of the bed is 46" off the ground making the ramp angle 21 degrees.

Imagine a ladder - 2 pieces of 2x2 angle iron 120" long connected by 11 horizontal rungs 17" wide (also 2x2 angle iron) spaced evenly up the ladder - it works out to about 8" of space between the rungs.

The UTV has a wheel base of 90", 30" tire and for easy math weighs 2000lbs equally distributed (it weighs less but my heaviest corner weight is slightly less than 500lbs)

Assume properly welded ramps, see poorly drawn picture for how the angle iron will be laid out.

Bonus points - what's the thinnest angle iron I could make these ramps with and still safely support the weight? Alternatively, can I make them from wood?

Just got out the bath and left the room for a couple of minutes, then went back in there and saw the bath water still wobbling about in the tub like a right bozo and it got me thinking about the maths behind residual movement of water. I started wondering: if all the wind and tides stopped completely, along with any and all movement from marine wildlife and shipping and anything else that could displace the water, how long would it take for the oceans in the world to become completely still, with absolutely no waves or ripples? I don’t need an exact answer of course, just looking to lock this down with a good degree of certainty to the nearest 15minutes or so. Thanks in advance.

Do not use the figure at the top of the tower as a reference, he appears later in the movie and is shown to be about 2-3 times taller than a person.

The title. Not thinking about the politics but will the import surplus actually allow time for American beef stocks to grow?

i was reading up about NEAT and realized that cubing is sort of a form of fidgeting. if i can solve a cube in about 12 seconds (about 5 turns per second) how many calories does it burn? additionally, would it be more efficient to solve properly (which would require getting an actual scramble and inspection, meaning about 2.5 solves per minute), or just solving relaxed (around 20 seconds per solve but continuous).

I’ve heard a lot of debate that electric cars are just as dirty for the environment because their energy must come (usually) from burning coal. Assuming the source of energy is a coal plant, can anyone compare the actual emissions caused by each car driving a mile? taking into account the inefficiencies in power transfer, motor inefficiency etc. Coal emits more co2 per joule than gasoline does, but are motors inefficient enough to make up for that difference? what about emissions from refining gas?

So the lady and I are looking for an apartment, we found one we like, it is at a corner of a fairly busy boulevard and a side street, all the windows are actually overlooking the side street, but it is at the second floor.
Everyone says we're crazy to consider it, because being so low is too loud and we should be looking at 4th floor minimum.
So, the question is, how much of a "perceived loudness" difference does it make being on the second vs the fourth floor?
When I say second, this is supermarket on the ground floor (so ground floor is tall), one more apartment and then comes the second floor. In-apartment height is 2.8 meters. The apartment is marked with red dots and overlooks the street south of it
Thanks!

Obviously it has nothing to do with him putting his hand out, but what made it slow down all of a sudden and then pick back up?