Human Definition and 895 Threads

I can't understand how eye actually works. From what I understand when I look at 2 objects of the same size The object that is further is smaller in the final image because light rays reflected from it take smaller surface at the retina (Here B is smaller than A because rays take less surface at...

How do you calculate the amount of pounds per square inch force on say a female human being approximately five feet tall at 185 pounds at rest being struck by a moving vehicle at motion by gravity with a curb weight of 2700 lbs going 4 mph.

I hve a question: IF there is no air resistance or ANY type of resistance in space, then how come an asteroid or fast moving object can crush a persons face in space (like in the movie: Gravity) My logic is the following: If you imagine a spring extended in space, and a fast moving ball hits...

I am making home automation model and I have few sensors installed to sense some changes in the environment to detect any changes. So these sensors provide me data , but I want to know what changes does Human body exerts on the environment it enters, so that I can install those sensors which...

So i was reading about how the magnetic fields of a neutron star are so strong that they would kill you at a certain range because it would affect the shape of atoms and mess with body chemistry. So what is the maximum number of teslas before a human would die, and how many teslas before you...

I want some suggestion about designing a hydraulic exoskeleton whose input would be the kinetic motion of the body...the force exerted by body would be used to give an input to the hydraulic system which would inturn give a larger force as output in real time.for example an arm with exoskeleton...

Hi I am having trouble locating resources for a topic as I do not know exactly what it is called, and I am looking for assistance. If you wanted to look at human performance and calculate the various ways a human could perform a task and how this would affect outcome by including "work done"...

It is said that around 90% of the cells in a human body are symbiotic bacteria living thanks to us. When we die, do most of them also die? Or do they manage to survive without us and find a new 'home human'? And opposite, when and how do we get all those bacteria after conception? Do we get...

Hi, I am referring to a pulse as one single 2π radian wave of preferably two frequencies at either end of the range. By two frequencies I mean that I would like to know if the detection of an audible continuous tone differs from their single oscillation frequency and/or intensity.

I know that if 2 eggs fuse early in pregnancy before a blastocyst forms in either one of them a true hermaphrodite will have formed in a human or animal that is not usually hermaphroditic. I also know that sometimes in multiple pregnancies, especially in multiple pregnancies that are more than...

Hi! Not sure if this is properly categorized,please correct me if it isn't. What if deja vu is just our brain misinterpreting 'reality' and exposing us to spacetime. Like skipping ahead in time(according to the definition of time in spacetime) but then it calibrates us back into the present...

I heard a claim bacteria can exist within human mitochondria, is there any evidence that is true ?. mitochondria"']https://www.google.com/search?q="bacteria+within+mitochondria"[/URL] only gets one hit, and the examples given are not human.

Hey guys, the question for this thread is, how can I find out what the heaviest object an average human can move effortlessly is? and by that I mean literally effortless to the point where it requires little to no force, even less than easy to move an object. One example I could give is picking...

If heart forces 4 litres of blood per minute and blood pressure is 125 mm of Hg column and we consider pulse rate as 60 beats per minute then by calculation power of heart comes as approx. 1.111 watts. If I consider the person is just lying down and obviously brain is also active . My question...

I never could understand this: the lens focuses light onto the retina so shouldn't the distance between the lens and the retina be the focal distance? It does not seem to be the case while I was trying to look around for the answer on the internet. And since light is focused on the retina, the...

What size propeller is required to lift a 180 lb person 30ft into the air consistently? Also, how powerful would the motor have to be to lift itself, the propeller, and person?

Hello, I am trying to build a personal (one-manned) propulsion system that will allow individuals to fly above the trees, preferably fast, and for long amounts of time. I plan to do so using propellers. The power will need to be plentiful and long lasting. These are some options that I am...

In the Earth forum, there is a thread about the Nepal earthquakes which started with a mag 7.8 earthquake. This thread is about the human impact. More than 2,200 confirmed dead in Nepal earthquake http://news.yahoo.com/aid-starts-coming-nepal-quake-kills-nearly-2-050207892.html International...

Does he failed to win a Darwin award ?. Try try again! So as you can see in this video: A Brave Man Hugs Young Bear Like His Son in the River... There's a fine line between being brave and being stupid.. In this instance we call him brave. Had the mother bear been in sight, we'd all be...

Homework Statement Say a human is moving through space with constant acceleration due to gravity. There are no external forces/torques on the body other than the force of gravity. The person applies an internal torque at some joint, let's say the knees, so that they bend. Assume the rest of the...

Sorry, this is a question on evolution. How did human female breasts evolve into such an important sexual organ? No other mammals other than humans seem to be interested in their corresponding female counterpart's breasts. They may be getting visually attracted, but do not seem to be interested...

Apparently the retina of humans covers about 65% of the surface of the interior of our eyes. But most light is focused around the fovea centralis and if it isn't focused around there, we lose resolution. I understand that at night it's better not to focus too close to the fovea centralis but...

There are a lot of books and videos that can teach you how to do math in your head. does any of it really work. Is there a certain book or video that you would recomend

I hope this is the right place for this... Question #1. How much can the human body stand multiple rapid G-force changes. Like let's say I made a vehicle that you could make sure all your body parts were 100% secured and it could move freely in space in any direction what would be the result of...

Hello, I have question about wind forces on a human body. (Wind force may be an incorrect phrase.) I have looked at a few other threads but haven't found an answer yet. Thisnisnfor a fictional short story I'm writing for fun. Info - SciFi A character in armored suit is hanging upside down...

This is quite interesting, I'm wondering if there's another way of creating human powered ferris wheel with mechanical parts. Can anyone give any suggestion? I'd love to get more information regarding this!

What differentiates a homo erectus from a neanderthal? They look very similar as they both lack chins and have brow ridges. To me, a neanderthal seems like a large brained homo erectus. Modern human skulls, on the other hand, look completely different. Thanks

I have just read that genetically modified e. coli can synthesize human insulin. But I wonder. Human (eucaryotic) genes have all kinds of introns, regulators, starting sequences etc. Bacteria don't have all of those. How can a procaryota produce an eucaryotic peptide? Has the insulin gene been...

What fraction of adult human cells are not replaced over a normal lifetime ?. see ... http://en.wikipedia.org/wiki/Ship_of_Theseus / [ aka "Trigger's broom" ]. I'm guessing it's a minority : brain and heart only account for about 3% of body weight.[ skeleton is replaced every decade , but...

I have a question. If an human have an artificial heart can the artifical heart support 220v? if the answer is yes. Can the human maipulate electricity? maybe is an stupid question but can you answer please

If our body temperature falls below 30 degrees C or so, it stops functioning properly and we die. 30 C seems still a rather warm temperature for normal chemical reactions to be able to occur, and in most environmental conditions inhabited by men it still represents a temperature gradient...

So I have a program that works for a guitar, and sinewave and a saw tooth wave . so If a have person sing a note, it should work for that right ? I am not talking about sing a whole song but just a note. so like when people sing the scales: do ra me fa so la ti do is should would for that right...

Greetings. Well I do not have enough time to pose all of my questions and ideas I can get this thread started off. So let's get right into it. The teeth of a Beaver incorporate a comparatively high percentage of iron in their construction, making them very strong and orange hued. (Also made to...

Is physical weakness the catalyst that started Human evolution?

Something I've always wondered about. It's neat to see a quantitative answer, finally. "To reach the new figure, Dr Lunter and his colleagues took advantage of the ability of evolution to discern which activities matter and which do not. They identified how much of our genome has avoided...

Nice to hear your comments...

Greetings, I don't have a magnifying glass/convex lens otherwise I would try to confirm this by experiment. Maybe I'll get one soon but to get things started. Let's say you have an object, with its own light source, and a convex lens with focal point f. The object is beyond 2f away from the...

There are many sources which say that a human cannot survive under the abrupt exposure to vacuum. What would happen if the exposure is not abrupt? Can a regularly clothed human survive in a vacuum chamber if we gradually lower the air pressure in the chamber to vacuum values for several hours of...

What would happen if I was standing in the LHC and I was hit by a (one) proton traveling at 99.999991% the speed of light. Would the collision burn a hole in me? or would it simply be going so fast that it passes through me without interacting with the particles in my body?

Hi, Today our teacher taught us about AIDS, and she said that it has no cure, because every time the genetic material of the virus replicates, it undergoes mutations, and a new type of virus is formed. Because of this, a lot of viruses are formed, each with a different genotype. That is why...

I was lately interested in learning how the human body weight changes through out the day. Like, how much weight (may be in just 10s of grams) is lost during sleeping, after bathing, after workout and like that. For that I would require a highly precise scale. But most commercially available...

If we pull/ push a weight of 10kg and dislocate it 1 meter the energy spent is 10 joules, can someone tell me roughly if 10 j is 100% can anyone tell me how much energy (calories) has been burned /wasted in excess? I suppose it can vary in different persons and by different factors, I'd like...

Hi pf, please could someone explain how a human centrifuge enables astronauts to experience a simulated gravity effect. I understand that if a centrifuge machine has a centripetal acceleration of 20 m/s^2 then they will feel a force of 2g. The thing that confuses me is that they are spun on a...

Hello guys, I read some articles recently about how touchscreens work by using the capacitance in human bodies. I'v seen the human body capacitance is quoted at around 100pf, is it the same when the human body is floating in mid-air, as if it is standing on the ground? My goal is to detect...

Hi all, Does anyone know what physics limits human tolerance to extreme g-forces? I know the average human can take g-forces 5-7 g, and a fighter pilot, with training and a G-suit can maybe get up to 12 g. And people can survive g-forces higher than this for a very short time. I know all the...

According to Pascal Law, when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container. Then why doesn't our entire body experiences the same pressure throughout the body when we press our finger. Isn't the entire body...

This might sound crazy, but I want to study pronging human life span. I am thinking of majoring molecular nanotechnology so that I can use this major to construct an artificial enzyme(medical nanorobot) that lengthens telomere (I know this is not the only issue of aging and death). I am not...

Hello I have a question that's been bothering me for a while now and I figured I'd post it here to see if anyone could put my mind at ease. (Sorry if I accidentally posted this in the wrong place) Given that people can only withstand a certain amount of force on their bodies (about 5 Gs)...

Is the current status of human species the result of a self-inflicted and unconscious artificial selection? We have heard about many cases of artificial selection, where the hand of the man “created” a new species by selecting individuals with particular characteristics of its interest and...

Putting a Human in Superposition I recognize the practical aspects of this would be absurd, but I must admit the premise of what it would take to put a human in a superposition of states is an amusing thought exercise and has some relevance towards me understanding actually in what scenarios QM...