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. M

    Designing a Pneumatic Arm to Lift 5kg Load 10m

    Hey I want to build a pneumatic arm that can throw stuff around (see attachment image). Before actually ordering the stuff i want help with some calculations. i want the arm to be able to push 5kg load (rectangular shaped) straight up into air. the arm/plunger area that makes contact with...
  2. B

    Finding angular velocity of telescopic arm

    Homework Statement So ,here is the question : The structure is shown in the picture. All I need is to find the angular velocity of telescopic arm BC ,in this current position. http://img197.imageshack.us/img197/3954/w6e.JPG Homework Equations Well,them simple ω=rXv/r\bulletr...
  3. T

    Best way to lift weight using mechanical arm

    Hi! For my finally year design project, I intend to try and solve the problems with existing shower bathing aids for the elderly and disabled. I won't go into details of what problems and how, etc, but I will give you an overview of the mechanism I intend to use. My product is essentially...
  4. F

    Calculating Torque and Lever Arm

    Here is the problem http://imgur.com/6KRKJQu Torque = force x lever arm We are told that the force is all the same so the only thing that would determine the torque is the size of the lever arm. The ones that I'm not sure about are B and C. The rest I think I have done correctly. Just to make...
  5. C

    What is the relationship between motor torque and force applied by a robot arm?

    Background: I'm a high school robotics team member. These first two images show the general design of the robot; the design is intended to use two arms, with "hooks" on the end (more like a bearing on a shaft, really), represented by cylinders, to hook onto a steel bar, and pull itself...
  6. T

    Angular acceleration of an arm

    Homework Statement Assume that a 1.20-kg ball is thrown solely by the action of the forearm, which rotates about the elbow joint under the action of the triceps muscle, the figure. The ball is accelerated uniformly from rest to 9.5m/s in 0.38s , at which point it is released. Assume that the...
  7. S

    ARM Cortex-M Machine Code Help

    Homework Statement Hey guys. I am just learning machine code for Cortex-M. There are a few exercises within the textbook, however, I am not entirely sure if I am doing them correctly. If you could possible look over my work to see if there are any mistakes, I would greatly appreciate it! They...
  8. siddharth23

    Force on Boom Arm due to suctioning sludge

    As shown in the picture, a vacuum created in the tank sucks in sludge from the gutters. The hose used for doing so is held in place by a structure called the boom arm. What magnitude force will act on the boom arm when the sludge is being sucked in? What I mean is, how do I estimate the force...
  9. joema

    Angular acceleration given force, moment arm and inertia?

    Homework Statement Find angular acceleration in deg/sec^2 given the following factors: - Total mass: 4889 kg - Moment of inertia: 4620 kg*m^2 - Moment arm length from center of mass: 1.5 meters - Force on moment arm tangent to mass: 1779 Newtons Homework Equations torque = force...
  10. T

    Affordable DIY Robotic Arm Project for Beginners | Step-by-Step Guide

    Hello, I'm a complete noob on the robotics. I got an idea, to build a really cheap robotic arm (~$60). I thought about using 4 servos (rotate the arm, move up/down the first part, move up/down the second part and open/close the grippers). As the bone material I found that 1m aluminium tube (2mm...
  11. N

    Greatest Lever Arm: Calculating Force at Elbow Joint

    Homework Statement The diagram is attached. It is asking which position has the greatest lever arm.Homework Equations The Attempt at a Solution So, I know that the elbow is the fulcrum but what I'm struggling with is how to draw the force arrow. Where is the force coming from and where is it...
  12. K

    Finding Torque within the Human Arm

    Homework Statement The arm in the figure below weighs 37.1N. The force of gravity acting on the arm acts through point A. Assume that L1 = 0.0720m, L2 = 0.300m and α = 11.8deg. Point A is 0.300m away from the pivot point. Fs is unknown angle degree from the horizontal. a) Determine the...
  13. M

    Torque of human arm when bending

    To find the respective torque that is need to bend the the arm at 180 degrees, 90 degrees and 30 degrees. The arm is not holding anything. Relevant equations and information τ=rFsinθ total arm weight =3.35kg upper arm length =19cm forearm length =28cm
  14. S

    How Do You Calculate Movements of a Robotic Arm?

    Homework Statement Given the following robotic arm: http://i.imgur.com/TIb1vOk.png and knowing that x_{c} = Lcosθ and y_{c} = Lsinθ, find expressions for x_{m} and y_{m} and show that: dx_{m} = -y_{m}dθ + (y_{c}-y_{m})d\phi Homework Equations (Shown on picture below) The...
  15. L

    Calculating torque with buyouant force and hardly definiable arm

    Hej Guy, Here I am again with a question on torque basically. Please see the image below. I have a half tube underwater. The tube have air inside. Now I would like to calculate the torque for this system. As you see the tube will move to a balanced position, but I don't how much torque...
  16. A

    Determining the Dynamics of a Robot Arm

    Homework Statement Here you are supposed to perform system identification to determine the parameters required later to perform model compensation in your PD control loop. The dynamic model of this single joint manipulator has the form τ = Ia + Bv + G(x), where a is angular acceleration...
  17. A

    Torque on a hub as a result from a flexible arm

    I'm working on a research project as a graduate student in engineering. I'm modeling a set of equations in Simulink and MATLAB derived from a journal entry. I'm a little rusty on classical mechanics as my specialization is electrical engineering. I want to model the angular torque on a hub as...
  18. K

    A String is Connected to a Vibrating Arm and Passes Over a Light Pulley

    Here is a tricky one (for me) that uses linear mass density and two masses. I don't really know which to do so I did both! Homework Statement An object can be hung from a string (with linear mass density μ=0.00200kg/m) that passes over a light pulley. The string is connected to a...
  19. Philosophaie

    Stars of Constellations exist in what Spiral Arm of the Milky Way Galaxy?

    The Milky Way is a Barred Spiral Galaxy 100,00 -120,000 Across. I was wondering if there is a website or list of what Stars of Constellations exist in what Spiral Arm. I there exists: Orion-Cygnus Arm Perseus Arm Scutum-Centaurus Arm Norma and Outer Arm Carina-Sagitarius Arm...
  20. F

    Robotic Arm Control β: Inverse Kinematics for 2 DOF

    βHi, I'm working in a project with an arduino mega 2560 controling a robotic arm with 2 DOF moved by servo motors. I want to make the arm lift vertically about 20 cm as if it would carry a transformer to a pole. I was thinking in inverse kinetics (don't know if that's the name in english) to...
  21. D

    Force in The X direction using Lever Arm

    Homework Statement What is the Force Needed in the X direction? I have a 500 lb Car and attached to the Wheel axle is a 12 inch long lever arm going straight down. The pivot point is at the axle and a cylinder is pushing the arm at the end of it. What force do I need to push this 500...
  22. T

    Calculating torque when the lever arm has mass

    Homework Statement A board is set on top of a scaffolding, with dimensions as shown in the diagram. The board weighs 15 kg. A man weighing 70 kg stands on the board as shown. How far out can he stand before the board falls? Homework Equations Torque: \tau = rFsin(\theta) Force due...
  23. K

    ARM tool to view register usage

    I tried googling on it, but can't find the answer, maybe the keywords doesn't accurate so always led me to definition of each ARM registers instead of what I want to know. What I want to know is: is there any tool for ARM that give some statistic on register usage? for example giving...
  24. M

    Need to find the spring constant and dampening coefficient of a humarn arm.

    Hey. Working on a project at the moment, where i have to simulate a human arm (hand and lower arm). I need to find the spring constant, k, and dampening coefficient, c. You got any good ideas on how i can do that? So far i tried by measuring the mechanical impedance, and saying the arm is a...
  25. C

    Deflection in a simply supported beam with a rigid arm underneath

    The attached question shows a simply supported beam with a UDL of 30kN/m and has a rigid arm underneath with a load. This question was a research one but unfortunately I have had no luck. I thought that this could be solved by doing moments for the arm but am unsure on whether that would...
  26. Z

    Balancing a spring and arm at 45 degrees

    I need to find what spring will balance an arm at 45 degrees the arm is 5m and can be considered as a UDL of 1.6kg/m the situation is that the arm starts upwards at 90 degrees and as it goes down it puts tension on the extension spring 5*1.6 = 8kN acting 2.5m along the beam which is...
  27. C

    Torque Calculation for Robotic Arm

    Hello, I hope I'm posting in an appropriate section. I'm trying to make a robotic arm using servos, but I'm not too sure what the max weight and lever arm length I could use. I know how to do the static torque calculations, but not too sure with the dynamic and rotational torque as the motors...
  28. H

    Trebuchet: Projectile Arm Length to Counterweight Arm Length Ratio

    I am working on creating a mid size trebuchet with a projectile arm length of 3 feet. The counterweight is about 3500 grams, with the projectile being 60 grams. I know that the ratio of the projectile arm length to the counterweight arm length changes depending on several factors, most...
  29. F

    Choosing a Robotic Arm for an Electric Engineering Project

    Hi, I'm an electric engineering student and I'm want to initiate a project to control a robotic arm. But i must first choose which arm i will work on and where to buy it. I want to make a position control, so i will need a feedback of the actual position of the arm. The control will be made...
  30. K

    Medical Paralyzed woman uses thoughts to move robotic arm

    http://www.reuters.com/article/2012/05/16/us-paralysis-robotics-idUSBRE84F1CM20120516 This is a remarkable achievement by the scientists. Now, we don't need limbs any more? :P I wonder how did the scientists find out where to connect each electrodes? How did they know which portion sends...
  31. G

    Analyzing Beam Deflection in Complex Loader Arm Structures

    Hi, I haven't done beam deflection before. My textbook shows the usual simple beams with a perpendicular force acting on it. This one is a lot more complicated. I'm pretty sure the forces acting in the horizontal direction have to be added into this some how. Can someone look at the...
  32. M

    Robotic arm revolute joint design

    I'm trying to make an elbow joint for a robotic arm that is actuated with a stepper motor and two gears. Here's a quick sketch of what I'm trying to do: http://imgur.com/mBlg7 The two bottom plates will be attached to the 'bicep' and the two upper plates will be attached to the 'forearm.'...
  33. Femme_physics

    How can a single electrical motor control a robot? or even a mechanical arm?

    So an electrical motor converts electrical energy to mechanical one. But an electric motor can just produce a single motion in of itself. How come connecting a mechanical arm to it allows a diversity of movements like rotation, verticial and horizontal motions to both directions!?
  34. N

    Swing Arm Velocity on Moving body

    1. Homework Statement What is the Average Velocity of the outer end of a 0.5m swing arm weighing 2.75 lbs (1.247 kg). with the weight evenly distributed the length of the arm. The arm extends horizontally at right angles to the moving body it is attached to, pivoting on a bearing at the...
  35. A

    Calculation of torque for motion control camera arm

    Hi, First post here, but I've been reading the forums for a while getting answers for various projects. I am currently working on a lightweight motion control camera arm (kind of a small jib arm, but with servo actuators). I've researched a lot to figure out what force I would need in...
  36. K

    Why does a Lever arm magnify force?

    Hey, I'm looking for an explanation of the why we observe T = F * d In the sense of two people applying a force to a lever arm and the person closer to the pivot point requiring more force to keep the torque in equilibrium. I can only find explanations in the sense of work and energy...
  37. M

    Eccentric rotation of a trebuchet arm

    If the word eccentric is not used correctly, please correct me.Homework Statement I am constructing a mathematical model of trebuchet throw. For the throwing part, I simply use the relation ΔE_p = E_k , so the change of potential gravitational energy goes into the rotational kinetic energy. I...
  38. G

    Force Calculation to balance arm

    Hello, I am after a little help on an applicaition, I need to calculate the force require to hold a pivoted arm in a position using a pneumatic ram. Basically the arms C of G is 740mm up the arm, and the arm weights 100kg. Roughly 1000N working at an offset of 147mm. The arm is 16 degrees...
  39. S

    MATLAB Help Needed: Add Axis, Draw Arm Pieces, Rotate Objects

    LEASE HELP! -Add an axis to current rectangle -Draw both piece of arm -rotate object first axis 20 degree --redraw. -then, rotate 2nd part about 2nd axis to -30degree my current code for rectangle is %RECTANGLE('Position', [x y w h]) w=4.5; %width h=.5; %height x=1.75;y=2.75...
  40. C

    Understanding the Mystery of Static Arm Reactions

    um, i placed my elbow on the table, and i think i mustve hit some ideal spot that actually caused a (static?) reaction up my lower arm. what i want to know is, what exactly it is, why did it happen, and why it only happens sometimes?
  41. D

    The arm of a crane at a construction site is 15.0 m long

    Homework Statement The arm of a crane at a construction site is 15.0 m long, and it makes an angle of 15.8 with the horizontal. Assume that the max- imum load the crane can handle is limited by the amount of torque the load produces around the base of the arm. What maximum torque can...
  42. A

    How to calculate weight an arm can curl.

    Homework Statement Suppose the length of your forearm is 34cm and its mass is 1.3kg. If your bicep inserts into the forearm 3.5cm from the pivot (the elbow), and your biceps muscle can produce a force of 800 N, how much weight can you curl? Model your forearm as a uniform rod. I have no...
  43. C

    Problems with velocity/acceleration involving clock arm

    Homework Statement A traditional watch has a second hand 2.0 cm long, from centre to tip a. what is the speed of the tip of the second hand? b. What is the velocity of the tip at 20s? 40s? and 60s? c. What is it's change in velocity between 15s and 30s? d. What is it's average...
  44. A

    Programming Robot Arm Offline: Methods & Tips

    How does a programmer programme a robot arm offline?ANd through what ways?
  45. N

    Terminal Arm Point P: Finding sin, cos, and tan for Θ in Standard Position

    Homework Statement The coordinates of a point P on a terminal arm of an <Θ (theta) in standard position are given, where 0<Θ<2pi. Determine the exact values of sinΘ, cos Θ and tan Θ 2h) (-2,6) Homework Equations r= X +y The Attempt at a Solution So, first i found r by...
  46. J

    Robotics and Automation of a Robotic Arm

    Good day everyone: I am planning on automating a robotic arm that is in my school's Instrumentation and Controls lab for my senior project, but I would like to know what are the things that I would have to take into consideration. What are the Steps that I would have to take to get this...
  47. X

    Ball colliding with an arm of an object that can rotate to it's axis

    http://imageshack.us/photo/my-images/195/spinner.png/ ^this is the object/spinner I am referring to. I am trying to code a physics based minigolf game in which a ball should be able to collide properly with the spinner object and the arms of it. However I am lacking in physical knowledge to...
  48. A

    Interferometers with unequal arm lengths

    One arm of a Michelson interferometer is one light second long, the other is one light minute long. We run photons through it one at a time. Do we see interference? And if so, when? After one second? One minute? Some other time? I've been reading a number (too many!) "layman's" books on...
  49. H

    Physics of man breaking arm falling into pool

    Homework Statement I am figuring out the physics of the scene in the movie Get Him to the Greek where an actor falls into a pool but breaks his arm by hitting it on the concrete edge. Mass of actor = 73 kg Mass of arm = 4.75 kg Force to break an arm = 73 N Duration of fall = 3.0 s Homework...
  50. E

    Calculating the Force of the Deltoid Muscle to Raise an Arm

    Homework Statement The main muscle responsible for raising an arm is the deltoid. The deltoid muscle connects at the upper end of the shoulder, extends over the upper arm bone (humerus), and attaches near the elbow. Effectively there are three forces involved in raising the arm: (i) the force...
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