Arm Definition and 215 Threads

  1. M

    Variable acceleration/velocity of an arm in motion

    I'm a karate instructor desperately trying to find a model or formula that explains what happens to the to speed and acceleration of a limb under varying conditions. If you assume that a limb has a travel distance of 3 feet, moving from stationary, and the limb weighs 5 kilos. If I assume...
  2. P

    Arm length and pitch speed in softball

    The big event of the softball season, the Women's College World Series, begins Thursday. One aspect I find interesting is that many of the dominant pitchers are very tall. Many of you are probably familiar with the underhand delivery of fastpitch softball, which implicates angular motion. The...
  3. B

    Solving Rotating Slotted Arm Problem

    Hi, I'm not able to work through part of a question and I would like some help with it. Firstly, I apologise for the lack of a diagram. The situation is this: First draw up the usual XY axes. A slotted arm (for the diagram it can be considered as a hollow retangular prism) has one end fixed...
  4. D

    Calculating Torque & Lever Arm for a Lunch Tray

    A lunch tray is being held in one hand. The mass of the tray itself is 0.201 kg, and its center of gravity is located at its geometrical center. On the tray is a 1.33 kg plate of food and a 0.285 kg cup of coffee. Assume lever arm of the thumb is 0.0620 m, lever arm of the finger is 0.113 m...
  5. H

    Calculating Work Done to Move Arm from Position 1 to 2

    An arm has a mass of 7.0 kg. Treating the arm as if it were a single point mass m attached to a rigid massless rod, determine the work that must be done by the deltoid muscle to move the arm from position 1 to position 2. (Position one and two have an angle of 30 degrees between them and it is...
  6. P

    Is that a pneumatic pump driving that arm?

    Hi... I've seen a lot of tractors, they seem to have a shiny aluminum on their arms.. Are those pumps?? What are the advantages of using them? And how to configure them, do they power by motor? Please explain in details, thank you.
  7. P

    Creating a "Mechanical" Arm with 2DOF: Questions Answered

    Hello, I have a question regarding creating a "mechanical" arm which would have the ability to move freely in 2DOF ( ie. lift up and back down , kind of like our human arms, but when it goes down, it can go down a lot further than we can ). I saw bots like ASIMO use those umm... looks like...
  8. A

    Determining arm length of catapult

    Hi, I have a big problem... I got a project on building a catapult. Easy, right? WRONG! We are supposed to determine the arm length without trial and error and I have no clue what to do. Please please help! Catapult is supposed to be built with 3/4" paper clamp as the only energy source and...
  9. A

    What Is the Required Muscle Force to Hold an Outstretched Arm?

    I can get pretty far in this question, but I can't seem to get the final answer. The problem is: Calculate the force required by the "deltoid" muscle, Fm, to hold up an outstretched arm. The total mass of the arm is 3.33kg. On the diagram, the pivot point I chose is the shoulder socket, and...
  10. M

    Comparing Data from Rotary Arm Sensor to Theoretical Square Wave

    I have collected 5000 points of data from a sensor on a rotary arm (which I was trying to control to move with a position time graph that follows the pattern of a square wave) My question is, once I've plotted the graph in excel, how can I overlay a perfect (theoretical) square wave to show...
  11. Q

    My Mobile Hurts my fingers hands then whole arm

    My Mobile Hurts my fingers ... hands .. then whole arm! Hi, My mobile went messed up for sum reason and i have stopped using it now. It used to make my fibgers hurt...it got worse and worse until it made my fingers numb in a matter of minutes if i used it. Thne it hurt my whole arm one day...
  12. D

    Optimizing Lever Arm Length and Material for Maximum Distance in a Mousetrap Car

    am doing mine for distance should i have a long lever arm or a short lever arm, and how long should it be? and should i use a like a rubber string or just a normal one and how long should that be? thanks if you can reply by today
  13. Dissident Dan

    Why does moving the point of force application increase torque?

    Well, we all know that the farther you move the point of force application from the point of rotation, the greater the torque. But why? I know the equations, but I am lacking a physical explanation of why this is. The best explanation that I've gotten is something along the lines of a...
  14. R

    News CIA Finds No Evidence Hussein Sought to Arm Terrorists

    linky: http://www.washingtonpost.com/wp-dyn/articles/A46460-2003Nov15.html CIA Finds No Evidence Hussein Sought to Arm Terrorists By Walter Pincus Washington Post Staff Writer Sunday, November 16, 2003; Page A20 The CIA's search for weapons of mass destruction in Iraq has found...
  15. Greg Bernhardt

    Monkey moves robotic arm with brain implant

    http://www.washingtonpost.com/ac2/wp-dyn/A17434-2003Oct12?language=printer
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