What is hand: Definition and 466 Discussions

A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "hand" and fingerprints extremely similar to human fingerprints) are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking.Some evolutionary anatomists use the term hand to refer to the appendage of digits on the forelimb more generally—for example, in the context of whether the three digits of the bird hand involved the same homologous loss of two digits as in the dinosaur hand.The human hand usually has five digits: four fingers plus one thumb; these are often referred to collectively as five fingers, however, whereby the thumb is included as one of the fingers. It has 27 bones, not including the sesamoid bone, the number of which varies among people, 14 of which are the phalanges (proximal, intermediate and distal) of the fingers and thumb. The metacarpal bones connect the fingers and the carpal bones of the wrist. Each human hand has five metacarpals and eight carpal bones.
Fingers contain some of the densest areas of nerve endings in the body, and are the richest source of tactile feedback. They also have the greatest positioning capability of the body; thus, the sense of touch is intimately associated with hands. Like other paired organs (eyes, feet, legs) each hand is dominantly controlled by the opposing brain hemisphere, so that handedness—the preferred hand choice for single-handed activities such as writing with a pencil, reflects individual brain functioning.
Among humans, the hands play an important function in body language and sign language. Likewise, the ten digits of two hands and the twelve phalanges of four fingers (touchable by the thumb) have given rise to number systems and calculation techniques.

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  1. N

    I Calculating the root of a number by hand

    Hi, is it possible, is there any formula that can help me to take root from (for example) 1,2 without a calculator (by hand)? For example, there is a cos(x) formula that can be calculated on the paper: $$\cos x=\sum_{n=0}^{\infty}(-1)^{n} \frac{x^{2 n}}{(2 n) !}$$ There is the Babylonian method...
  2. bmhiggs

    Recharging a Battery With a Hand Crank?

    Could a normal rechargeable battery (meaning the kind you plug into a usb port or electrical outlet) be recharged with a hand crank generator (assuming it was generating a sufficient voltage)? Would there need to be some kind of converter to make it possible, or just connect some +/- leads? I'm...
  3. benorin

    Relief of Complex Gamma Fcn — was this hand drawn?

    This pic is from an older text called Tables of Higher Functions (interestingly both in German first then English second) that I jumped at buying from some niche bookstore for $40. Was this hand drawn? I think I’ve seen was it that mathegraphix or something like that linked by @fresh_42...
  4. shivajikobardan

    MHB Calculating Probabilities in Poker Hand: An Example

    An example of how probabilities are calculated in poker hand. https://lh5.googleusercontent.com/pCynfBFNqfR00y8rEKWoXYkbSCGR310FpejMJ_iGWlwD7ttkCZjunp-TLKFMmU0A94CDsR4Bb-X8i6ai8RxiLLPdWlf1j9g6BZdjq1ppPZzp0JZOBjCVqwvKCK9XmGfg7Ks7VnN4IoWZIY3gqWvmKw Probability and Statistics with Applications: A...
  5. L

    Engineering Hand tool boundary conditions - Forces determination

    Hello, I' m trying to make a linear static analysis (Finite Element Analysis) on the following hand tool. I want to determine the boundary conditions. In order to do that I have decided to use a force couple to represent the forces that a bolt exerts on the jaws of this spanner. Despite using...
  6. bluesteels

    Confused about applying the Right Hand Rule (RHR)

    the answer is attractive. but i don't see how this is how I draw mine and I use the RHR on the magnetic field between the two wire and I got the force is opposite
  7. MatinSAR

    Experiment with an Electroscope, a Charged Rod and my hand

    I know that if we bring a positively charged rod closer to the electroscope, charges of electroscope are separated and the leaves of the electroscope get away from each other. but what happens if we touch the positively charged rod with our hands and then move the hand and rod away?
  8. shivajikobardan

    MHB Find Resources to Solve Knapsack Problem by Hand

    Really need this. Tried googling but not many. 1 or 2 are there. I want this algorithm solved by hand to some problem. IDK what kinds of problems exists. but one is knapsack problem. there is analytics vidya's tutorial but I want sth else, more direct, more clear...Any resource you can show to...
  9. rylest

    Stuck on complex pipe system bending moment hand calcs

    Some more details on the system are that L1 is very long (close to 100ft) and L2 is close to 30ft (the vertical pipes). The piping is all schedule 40 1/2" OD. Moment of inertia is roughly 10^-8. Components are about 2kg each. The distance of the pipes horizontally is small (around 2ft). Pressure...
  10. D

    Friction force on each foot and on each hand of a person

    I get how to solve (a); my method involves finding the net torque about the man's hands and setting it to zero, which can be used to solve for the normal force acting on his feet and the normal force on his hands can be solved using Newton's first law. Then divide by 2 for each to get the normal...
  11. srfriggen

    How to graph by hand: y=log((x/(x+2))

    I first attempted to find the x and y intercepts, algebraically, and discovered there were none. I then split the equation into y= log(x) - log(x+2) to see if that would give me any insight. It did not. I used a graphing calculator and saw many similarities between x/(x+2) and log((x/(x+2)) but...
  12. S

    B Is it really possible to slap my hand through a table?

    I've just started to learn about Quantum Tunneling and heard that if I were to slap my hand on a table it's theoretically possible for my hand to go through the table. Is this really possible and if so, does the fact that this is even possible provide evidence that we could be living in a...
  13. K

    Sketch the function by hand -- I'm confused on how to do this

    Sketch by hand the function determined as f(x) = 1/28 (7√−16x^2 + 16x + 5 + 12) and then From the sketch, determine the domain and range of f in interval notation. Hint: Interpret f as part of a circle. You must include in your solutions the inputs and outputs you used to help you sketch the...
  14. 1

    Can some liquid hand soaps smudge your eyeglass lenses?

    My control variables are 1. water hardness level, as I live in Florida, and I lodged at a Ritz Carlton also in Florida. I'm not, in any way, affiliated with any corporation herein. I'm not, in any way, affiliated with any corporation herein. 2. my eyeglasses with $700 USD Nikon SeeMax Ultimate...
  15. Limebat

    B Can you use hand tools on the moon?

    No, this isn't a homework question. I'm genuinely curious; If I were to magically teleport and happenstance with a shovel and survive the harsh climate, could I use said shovel? Maybe hand drills? I would assume the shovel would be a class one lever, and thus the moon's lower gravity would...
  16. M

    Electrical Fleming's "right hand rule" is not working for me. Why?

    I built this DIY generator on the thought that the flux from two north poles of a magnet would be attracted to an iron core of a toroid coil. I wrapped the 4 inch OD toroidal coil with about 700 turns of 27 awg wire. The toroid coil is stationary with the magnetic flux rotating around the coil...
  17. K

    Difference Between FEA Result and Hand Calculation in Beam Bending?

    This is the analytical working out. I substituted the value of 306mm ( the maximum length of the beam) to find the maximum deflection along the Z-axis. Which came out to be -2.39mm. But according to Ansys the average deflection is 0.3mm and the maximum deflection is 0.8mm. This is the Ansys Values.
  18. S

    Art Notation for drum parts when scores were hand written?

    In the days when scores were written by hand, how were parts for drums written? It's clear that ordinary notation is sufficient to indicate the duration of dumb beats - although writing each beat for a drum would be tedious. Was there some system of abbreviation? Did composers attempt to...
  19. N

    Right Hand Rule for Electromagnets

    Ok I’m trying to understand the right hand rule in relation to electromagnets. Since I’m a visual learner I made myself a little diagram. Is my little diagram correctly showing the flow of electrons relative to the magnetic poles? Also does the core and helix being slightly curved affect the...
  20. S

    Confusion about the right hand rule (Lorentz Force)

    Hello. I am trying to do a basic experiment to demonstrate I⊗β≈ƒ or current cross magnetic field results in a force perpendicular to the plane of the other two. But every time I test this out, it appears I get a force in the same direction as the magnetic field. Here is my experiment: Strong...
  21. J

    Left Hand Rule Applied to a Winding

    All illustrations of direction of force in motor has this form. For the following specifically the rotor. I'm confused where is the direction of force. It uses winding and there seems to be current and force in every side of the winding (applying left hand rule). So where does the principal...
  22. FEAnalyst

    Fatigue life hand calculations based on static FEA results

    Hi, advanced FEA programs allow their users to perform fatigue analyses. However, there are still many programs where such simulations can't be performed. I've heard that in such case one can use results obtained from regular linear static FEA to calculate fatigue life manually. Theoretically...
  23. PhysicsTest

    Two variants of the Right hand rule

    I found two variants of Right hand rule one of the straight wire and to find the direction of the magnetic field i need to use the below method Method1: And to find the direction of magnetic field produced by current in a loop Method2: In method1 the thumb was pointing in the direction of...
  24. J

    What type of letters are used in aero-engineering when hand writing?

    Which type of letters is rule to use in aero-engineering when hand writing? All capitals-block letters, cursive, upper and lower case-block letters. .?
  25. A

    Understanding Torque: Applying the Right Hand Rule in Real Life

    What does right hand rule torque mean in real life? engine crankshaft produce torque,if apply right hand rule to crankshat that will mean that torque is act in crankshaft axiis of roatation,which mean axials berings will have huge load on it,,that is not the case in reality,axail bering don't...
  26. G

    Logarithm calculation by hand

    From the log tables: ##log(890) = 2.9494, \space log(12.34)=1.0913, \space log(0.0637)=\bar{2}.8041## I calculate by hand: ##\begin{array}{r} &2.9494\\ +&1.0913\\&\bar{2}.8041\\\hline &2.8448 \end{array}## Thus: ##log^{-1}(2.8448) \approx 699.6 \space## Which is the correct answer. Now I...
  27. SamRoss

    Do mathematicians still work on proofs by hand?

    With automated theorem proving, what is left for mathematicians other than perhaps inputting weird axioms? Or are the machines not as sophisticated yet as I'm assuming they are?
  28. E

    How to make home-made hand sanitizer

    Hi guys, sorry for the uneducated question I'm about to ask. Hand sanitiser is impossible to come by in my city with everything that's going on and i require some for my workplace. My understanding is the active ingredient is essentially alcohol, so i have decided to try make some sanitiser...
  29. L

    Need a Hand Calculating the Maximum Load on a Structure

    Basically looking to find out what the maximum amount of load you could put on the center of a structure like this would be, in theory. Top Beam: The top "Beam" of the assembly in the drawing is 3"x 3"x 3/8" square tubing, 112.5" long Supporting Beams: The beams supporting each end of the Top...
  30. P

    Magnetic Forces & Moving Wires: The Right Hand Rule

    OK so a wire with a current creates a b field in accordance with the right hand rule. Now moving charge will feel a force (if its moving in the correct direction) while stationary charges will not feel a magnetic force. What I am curious about is if we move the wire itself, will a stationary...
  31. T

    Low level hand held lazer therapy for hair works?

    Hi, does low level hand held laser therapy work for stimulating the hair follicles, scalp and improve your hair’s appearance with a couple of fifteen minute sessions per week? if yes how much do they cost?
  32. R

    Would a longer lever require less force to hand pump water? (PHOTO)

    I think that it would take less force to pump water based on the lever principle. But I'm not so sure! Here's a drawn photo.
  33. S

    Wood/Glass/Metal Using a hand saw with ratchet-like teeth

    I tried to saw a piece of wood with a hand saw. Its teeth have an unsymmetric, ratchet-like bias that allows you to pull the saw, but they dig into the wood and refuse to move when you push. (This is not about the blade sticking in the gap after cutting halfway -- I can't even cut a couple of...
  34. P

    Building Electrionics by Hand

    I just finish course on electric circuits and soild state Devices I want to start learning to apply what I studied I want to build electrionic circuits by my hand Can you suggest books or courses to teach these things??
  35. thebosonbreaker

    Can Fleming's left hand rule be used for induced currents?

    Hello all, I understand the distinction between FLHR and FRHR. The LHR is used primarily for motors, while the RHR is used for generators/induced currents. For a conductor moving between magnetic poles, we can use the RHR to predict the direction of the induced current. According to the diagram...
  36. BWV

    I Hot hand fallacy fallacy

    Authors revisited the famous Gilovich, Vallone, and Tversky paper from 1985 that 'disproved' the existence of a 'hot hand' or serial correlation in shooting attempts and found a subtle sampling issue, that when corrected for, actually proves that hot hands exist...
  37. R

    B How to explain "the right hand rule" to an alien universe

    Suppose we are in communication with aliens who live in a different universe. I know, that's impossible, communication requires the exchange of mass or energy, which implies that we live in the same universe. But suppose it is true. I am wondering, can we and the aliens, via this communication...
  38. J

    MHB Solving Minute Hand Distance from Ground Graph Problem

    I'd like to know how to solve this. I'm pretty lost as to how to solve this. I want to say that the graph would look periodic because of the graph of the time would go down and then go back up again, but I really don't have anything concrete. The question states: The circular clock has a...
  39. D

    MHB How far to the nearest hundreth cm, does the tip of the hour hand on a clock move

    How far to the nearest hundreth cm, does the tip of the hour hand on a clock move in exactly 3 hours if the hour had is 2.00 cm long? I think you are supposed to use arc length formula. This is what I got so far: s=r(radian symbol) = 3=1(radian symbol)
  40. L

    Electromagnetic Induction and Faraday's Law w/ Right Hand Rule

    Homework Statement Homework Equations Right Hand Rule The Attempt at a Solution I am not understanding why the force is left. I can only figure out that the current in the solenoid is moving clockwise because of the right hand rule. From there, I see that the induced current might be...
  41. S

    Wood/Glass/Metal Video about modifying a new Ryobi electric hand planer

    This is an interesting video where a shipwright shows how to modify a new Ryobi electric hand planer to correct some of its defects.
  42. I

    Hand stalls when writing certain numbers?

    When writing the number 3, my hand seems to stutter or stall slightly before i complete the 3. This only happens some of the time though. I am only 16 years old but I have also suffered a minor concussion. Does this happen to anyone else, could it correlate with a deeper issue?
  43. M

    The right hand rule in a magnetic field

    Homework Statement An electron moving in the -z direction enters a region that has a uniform magnetic field in the +y direction. When the electron enters this region, what direction will it be deflected in? Homework Equations F=qv X B The Attempt at a Solution I tried answering this question...
  44. grandpa2390

    Automotive Recharge an RV battery by hand cranking a generator

    If you've seen breaking bad you probably already know what I'm asking. in this episode I'm watching, they are hand cranking the generator to recharge the battery. They are moving nowheres near as fast as the motor would have spun it. My dad had a hand crank device that was, more or less, a toy...
  45. Spinnor

    I Accretion disc poloidal magnetic field, right or left hand rule?

    If your fingers of one hand curl around the axis of rotation of the accretion disc of a massive black hole and your fingers point in the direction of the flow is the direction of the central twisted poloidal magnetic field given by a right hand rule, a left hand rule, no rule? Is there a simple...
  46. Y

    Why does Fleming's right hand rule apply for induced current

    I know that the right hand rule applies for induced currents, and the left hand rule is for motors, but why? It doesn't seem to connect with any other physics laws and is very counter-intuitive that the current will flow in one direction rather than the opposite direction if both are...
  47. JTC

    I Why does the cross product operation adhere to the right-hand rule?

    (First, I am aware there is no cross product in higher dimensions. I am aware of differential forms. I am aware of the problems with the cross product. I know enough to know what I don't know. but set all that aside.) With that, could someone help me, by properly phrasing the cross product...
  48. D

    Fleming's left and right hand rule - how do they work?

    Homework Statement AC production and relationships that determine movement and current flow direction from Flaming's left hand and right hand rule. Homework EquationsThe Attempt at a Solution Left hand rule for motors- right hand rule for generators The thumb, index and midle fingers are all...