What is Arm: Definition and 215 Discussions

In human anatomy, the arm is the part of the upper limb between the glenohumeral joint (shoulder joint) and the elbow joint. In common usage, the arm extends through the hand. It can be divided into the upper arm, which extends from the shoulder to the elbow, the forearm which extends from the elbow to the hand, and the hand. Anatomically the shoulder girdle with bones and corresponding muscles is by definition a part of the arm. The Latin term brachium may refer to either the arm as a whole or to the upper arm on its own.

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  1. A

    Quick Question about Torque and Tension

    Homework Statement A meter stick with a mass of 260 g is supported horizontally by two vertical strings, one at the 0-cm mark and the other at the 90-cm mark A) What is the tension in the string at 0 cm B) What is the tension in the string at 90 cm C) The string at the 90-cm mark is cut. What...
  2. A

    B Gravitational Wave Stretching: LIGO Arm vs Light

    I'm puzzled that the stretching of space by a gravitational wave stretches the LIGO arm but not the light within it. Because we are told that the red shift of a distant galaxy is caused by light being stretched by the expansion of space (the universe).
  3. D

    Common practice for unloading arm drainage

    Hello all, Does anybody know the common practice used for draining an unloading arm which contains and transfers Volatile Organic Compounds (for example LPG, propylene, ethylene) and which is installed in a breasting island (away from land but not necessarily too far)? I searched the web and...
  4. Alexanddros81

    Determine the angular speed ##\dotθ## of the arm OC

    Homework Statement 13.30 The colar B slides along a guide rod that has the shape of the spiral R = bθ. A pin on the collar slides in the slotted arm OC. If the speed of the collar is constant at v0, determine the angular speed ##\dot θ## of the arm OC in terms of v0, b, and θ. Homework...
  5. rkatcosmos

    What is the rotational velocity of hard disk actuator arm?

    0 down vote favorite There is a lot of material discussing the rotational speed of the magnetic disk in HDD but not about the rotational speed of actuator arm. What are the typical actuation speeds of the actuator in HDD? This information will be used in the design of a fast shutter system...
  6. kolleamm

    I Arm reaching algorithm determine angles

    I'm trying to find an algorithm for extending an arm as close as possible to an object. There's two bones the upper arm bone and the lower arm bone, and three points : shoulder , elbow, hand How can I figure out the closest possible configuration towards a fourth point which is the object it's...
  7. kostoglotov

    Why is pipelining easier on a RISC vs a CISC?

    I know very basically what pipe-lining is. My understanding is that the output from one "computing element" (usually a small set of instructions solving a simple task, such as say, finding a geometric mean) should flow immediately into the input of the following "computing element" where it is...
  8. T

    How is power transmitted in an exoskeleton arm?

    In an exoskeleton arm that is designed with the purpose of enabling the user to lift more weight than they can unassisted through multiplying the force / power applied by that user, where exactly does the power that is generated by the motor get transmitted to and how does it get transmitted...
  9. S

    Rotational Motion Question, lever arm with two masses

    Homework Statement [/B] A uniform rigid rod with mass Mr = 2.7 kg, length L = 3.1 m rotates in the vertical xy plane about a frictionless pivot through its center. Two point-like particles m1 and m2, with masses m1 = 6.7 kg and m2 = 1.6 kg, are attached at the ends of the rod. What is the...
  10. Diptangshu

    Are Moment Arm & Common Perpendicular Different?

    Not only the Problem I have attached in Picture, but there are few more where I get different answer while solving by taking Moment Component and by Common Perpendicular. [NB : The problem Stated in 'Engineering Mechanics' by Ferdinand L. Singer. Process 3 is what I did, Process 1 is what is...
  11. Dusty912

    What is the angular acceleration of an arm

    Homework Statement what is the angular acceleration of the arm when theta equals 45 degrees. v=2 m/s picture is attached Homework Equations law of sites law of cosinesThe Attempt at a Solution [/B] so I used the law of sines to resolve side r as being 579.555 mm now I now I need to take time...
  12. Dusty912

    What is the Velocity of Point P relative to Point O in a Linkage Arm System?

    Homework Statement I uploaded the picture to this problem, but it asks what the relative velocity of point p is to point o when theta is equal to one and the derivative of theta in respect to time is also positive 1. the picture explains everything. Homework Equations Tangential velocity...
  13. J

    Adjustable spring tensioner for 90deg rotating arm

    Hi all, I'm an electrical engineer and I'm part way through the design of a little project and I'm struggling with a mechanical element which I'm hoping someone may be able to assist with. I'm going to keep the finer details out of this to keep things simple and just focus on the issue. This...
  14. aon3t

    Torque applied on a lighting column

    Greetings! I am currently making a program which is about lighting columns. And I am currently at a halt because I need some basic physics done before I can complete it. I have a lighting column which is L = 8 m D = 0.087 m M = 69 kg I have a force, applied from the wind load, at F = 1235...
  15. V

    How Does a Pendulum on a Rotating Arm Behave When the Arm Stops?

    Scenario There is a pendulum suspended on an arm that rotates a certain angle in the horizontal plane. The arm suddenly stops, how far will the mass of the pendulum be displaced in the horizontaly? Thought so far: The momentum of the arm will be L=IW and when it stops I think the mass at the...
  16. R

    B If the pedal crank arm length of a bicycle increases....

    You have 2 bikes. They only differ in 1 way. The length of the crank arm (where pedal attaches) https://en.wikipedia.org/wiki/Crankset How will these bikes differ when riding? Is one harder to pedal than the other? Why?
  17. PM22

    Formula to calculate force as a function of angle

    What formula can I use to calculate the force I need to apply to a sliding arm that makes a point contact along the edge of a rotating arm attached to a shaft driving a load in order to push the rotating arm to rotate the shaft? The rotating arm is 1 cm wide. The load at the shaft is 1 Nm...
  18. Kernul

    How Do You Calculate Robot Arm Motion to Reach Specific Coordinates?

    Homework Statement My professor posted this problem on his page as a self-assessment for the students and said that you just need some analytical geometry notions and trigonometry to solve it, although I don't quite get how to solve it. This is the problem statement: Considering the articulated...
  19. ShayanJ

    C/C++ ARM programming in ubuntu with C\C++

    I'm thinking about learning ARM programming with C\C++(I think C is a better choice though). But I don't know what tools I can use on linux(ubuntu). I prefer to use open source software. Is there any suggestion? Thanks
  20. Haim

    ∆ energy when impacted by robot's arm

    Hi, This problem relates to my final's project. I'm trying to quantify an impact on a human hand from a robot. I've thought about it in Watts, Joules and Newton's. But I ran into a problem when I thought about it like this: If I have the mechanism (in the drawing)- its energy when falling...
  21. L

    Mechanical question -- Mechanical arm with special constraints

    Here in this case an arm in special constrain. The arm is capable to rotate around the main center if force is applied to the center. The torque practically generated by the force that is pushing Tarm. Tamr rotates and pulls with more or less the same force at the top that horizontal force then...
  22. B

    Mechanical advantage: lever arm

    Homework Statement In order to lift the 30 kg mass, a Force F is applied to the massless meter stick shown below. How much weight must the fulcrum bear if the mass is to be lifted? Homework Equations R/E = l/L The Attempt at a Solution So I began with the formula above and this is my set up...
  23. M

    I Second moment of area of a quad copter arm?

    does anyone know how to calculate the second moment of area of a typical quadcopter arm like this? what should I approximate the cross section as...
  24. RoboNerd

    Angular Acceleration and Moment Arm

    Homework Statement [A rocket has landed on Planet X, which has half the radius of Earth. An astronaut onboard the rocket weighs twice as much on Planet X as on Earth. If the escape velocity for the rocket taking off from Earth is v , then its escape velocity on Planet X is a) 2 v b) (√2)v c) v...
  25. x2017

    Trouble Determining Moment Arm (aka Lever Arm)

    Homework Statement Homework Equations ΣM=Στ The Attempt at a Solution I know how to get the net torque about point P, but I am having difficulty determining where the moment arms for each force should be. I did 9 simpler questions before this no problem, but this diagram is a bit more...
  26. M

    Finding number of rotations till arm breaks (circular motion)

    Homework Statement A 400 g steel block rotates on a steel table while attached to a 1.20 m -long hollow tube. Compressed air fed through the tube and ejected from a nozzle on the back of the block exerts a thrust force of 4.91 Nperpendicular to the tube. The maximum tension the tube can...
  27. C

    Confusion about how to identify lever arm

    Homework Statement A rotational axis is directed perpendicular to the plane of a square and is located as shown in the drawing. Two forces, F1 and F2, are applied to diagonally opposite corners, and act along the sides of the square, first as shown in part a and then as shown in part b of the...
  28. M

    Is a Torque Arm Necessary for Installing a Radial Hydraulic Motor?

    Hi, is it really needed to use a torque arm for installation of radial hydraulic motor? what if I only used its flange connection to put it in the system? is there any risk?
  29. A

    Load Acting on Robot Arm Driven by Electric Motor

    Hello all I have a doubt with the load concept acting on a beam. Consider a robot arm, actuated using Electric motor. When the arm is static and hold in position by the motor, Does the Gear ratio reduce the load acting on the motor due to the Gear ? Or when the arm is static, the Gear system...
  30. K

    A grinder has a 6.01 kg steel block on a 1.46 m long arm.

    Homework Statement A grinder consists of a 6.01 kg steel block on a 1.46 m long arm that spins around a table. If the angular acceleration is -1.62 rads/s2, what is the coefficient of friction between the steel block and the table? I'm having trouble with attempting the question, especially...
  31. GPP

    Troubleshooting Jerky Motion of a Robot Arm: Expert Tips & Solutions

    Dear friends, I have designed a robotic arm driven by servo motor via a planetary gear box.I have used taper roller bearing & deep groove bearing to hold the driven shaft.The distance between two bearings is 10 mm .When I turn ON the motor, the motion of arm is jerky.Also, I've used lamina...
  32. L

    How do I Calculate Normal and Applied Forces on a Branch Wheeled System?

    Dear Physics lover friends, I am in the middle of something and I would like to ask a question on how to solve this branch wheeled problem. The yellow lines are the branches, they have one wheels on them and the wheels are on a circular path. I would like to know how much the normal force A...
  33. DrTuring

    Non-centered Rotating Arm with Hinged Weight

    Homework Statement I have a an arm with an attached hinge and weight that is rotating inside of a circle, but important the arm is not rotating about the center of the circle. The arm is spinning fast enough so that the weight is always making contact with the edge of the circle. I need to...
  34. D

    Calculating Friction Force and Bore Size for Robotic End of Arm Tooling

    Good morning, I need some help on a robotics application. We have an electrical component, which fits into a plug to have software loaded; a robot picks up the component, puts it in the plug, and once software is loaded, moves the component to an unload bin. Space constraints mean we used a...
  35. Jide Orisanaiye

    Robot Arm Design: Lagrangian of 2-Link, 3-DOF

    I need to determine the Lagrangian of a 2 link Robot arm with 3 degree of freedom.
  36. LouisTo

    Need help please -- Severe Occupational Pain: Design a "floating" arm

    Hello folks. My name is Louis and I am the owner of a nail salon. I've suffered from pretty severe neck and shoulder pain for at least a year or two now, to the point of tingling and numbness radiating down my arm and leg when I crack my neck to try and relieve the tension. This is a huge...
  37. Curtph

    Can I stick my arm in past the event horizon?

    So the event horizon is the distance from the singularity where escape velocity exceeds the speed of light, right? Well let's say I am standing next to the event horizon, RIGHT next to it. What if I stick my arm in past the event horizon, then pull it out. I can't do that, right? Why not...
  38. P

    Arm blade mechanism for Cosplay

    Hello everyone! I'm making a costume of a game character and I think I need some guidance regarding the mechanical aspect. I asked this question on a cosplay site, but they suggested I might get more help here. So I'm going to cosplay this character on an anime convention: As you may have...
  39. C

    How to calculate the angles that define the position your arm is in

    I have 3 points ##S##, ##E##, and ##W## each with ##x##, ##y##, and ##z## positions. ##S## is always at ##[1,1,1]## ##S## is connected to ##E##, and ##E## is connected to ##W## by a line. I want to calculate the azimuth and polar angles between ##E## and the vertical, and the azimuth and...
  40. M

    Lift capacity of a spring loaded arm

    Hello all, Yet another problem on engineering mechanics. This time I have a spring loaded; counterpoised arm: Something like this- http://www.akwmedical.com/files/imagecache/cart/SK2323_1.jpg http://t3.gstatic.com/images?q=tbn:ANd9GcTUCvnSKhKEbs4uNiOLg2TGU3p0quUrSp8Uh4QXqt5m4eIEf6_ISA What it...
  41. C

    Calculate Arm from Torque and Force vectors?

    Hi all, If Torque = Arm cross Force Is it possible to calculate the arm from the torque and the force? I have tried to solve this using cross product of torque and force to give me the arm direction. Then normalizing the result and multiplying by torque magnitude / force magnitude. However I...
  42. RabbitWho

    Why can I feel hiccups in my left arm?

    Also, when I swallow a tablet with a big gulp of water I can feel it in my left arm too. Usually just above the elbow. I'm guessing, because it's the left side, it has something to do with my heart. I'm not hypochondriaking, I'm just curious.
  43. DrowningKthnx

    Force required to keep arm in position

    Homework Statement Lawrence is holding a 9kg dumbbell in his hand with his elbow flexed 90degrees. The horizontal distance from the center of mass of the dumbbell to the center of Lawrence's elbow is 33cm. The horizontal distance from the insertion of his elbow flexor tendons to his elbow is...
  44. G

    Find Forces on Hand and Arm Holding a Ball

    Homework Statement When an object is static (not moving), forces and moments must balance to zero. A moment here is defined as the force applied to an object multiplied by the distance from the point of rotation (torque). A simple way of thinking about moment balances is to consider a seesaw...
  45. C

    Solving a Lever System: Lever Arm and Load Lengths

    Forgive me if this is in the wrong category. I have a product I am working out - I am a programmer and electronic engineer by trade, which didn't include a lot of work with physics principles. I have a lever system which seems simple - but the trick is, my load is acting as a lever too...
  46. R

    Force needed to open 1000 lb swing arm

    Hello: I am working on a machine for a non-profit to build homes in developing countries. I have laid out the basic machine concept and then became stuck trying to figure out how to open the 1000 lbs machine with only manual labor. The machine sits generally vertical with the opening side...
  47. M

    MHB How to Solve a Terminal Arm Word Problem and Using Latex

    Would this be an okay way to go about solving the problem? Also, how do I use Latex?
  48. U

    Angular acceleration of a falling arm

    Homework Statement Assume your arm is a solid rod, 0.740 m in length, free to rotate about your shoulder (so its moment of inertia is (1/3)ML^2). If you hold your arm out sideways, and then completely relax your muscles, what is the initial downward angular acceleration of your arm? Homework...
  49. S

    Problem with the weigth of the moment arm

    Hi A rod comprises a counterweight (a) a handle and a hook which hangs mass (m), the rods mass is 400g counterweight mass (a) = 1600g and the rod is 0.8m long. Equilibrium exists when the handle is at position X = 12.0cm How I did 1: calculated the length of the handle to (m) which was...
  50. haael

    Whom did cnidarians arm agains?

    Hey. I'm not a biologist, but I love to read about the evolutionary origins of different species. I also realized that the current knowledge on this matter is still incomplete. Now, when reading Wikipedia about cnidarians, ctenophora and other primitive types, I started to wonder. Cnidaria...
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