Jump to content
Mechanical Engineering

About This Club

this club is going to help you to understand the kinematics of machines, we will also discuss the different types of mechanisms. it also provides the tips to groom your personality. just share your knowledge and help the others to learn and make the world develop.

Club Types

Engineering subjects
  1. What's new in this club
  2. New whasap group for engineering questions kindly join https://chat.whatsapp.com/5xJy8qZh79wJFO2fcDpqLx
  3. What are Z-Kinematics U-Kinematics? I've never heard these terms before, so I'd be interested to know what you are talking about.
  4. Hello sir, i need an PDF or PPT files about Kinematics of Machines to Study for the both Z-Kinematics and U-Kinematics. If Possibles please share the files through Mail Mail id :kabilmech66@gmail.com Thank you Best regards....
  5. Be sure to check out the new post at Mechanics Corner. It poses a challenge problem for each of you to work on. Do you really know kinematics of machines? Find out!! Try the simple problem posted over at Mechanics Corner now. DrD
  6. I was able to answer my own question. The result is posted at the Mechanics Corner, so please read it there. DrD
  7. In terms of four-bar linkages, most of them obey Grashof's Law, but evidently a few do not. Those that do not are called "non-Grashofian" or "triple rockers." I have a difficult time visualizing a triple rocker. The name implies that no link can turn a full revolution. Can any of you point me to an example, a problem discussion, or any other information regarding a Triple Rocker linkage? DrD
  8. The original question posed was this: "what does a weighing machine measure our weight or mass?" To measure anything simply means to compare an unknown to a standard of the same type. Thus to measure a length of string, you compare the unknown length to the length of a ruler and discover that it goes, for example, 5 and 1/4 times. Thus the unknown is 5.25*(ruler length). OK, I'm sure everybody knows that part. To compare to items, they must be of the same type. Thus you can compare one length to another length, but you cannot compare a length to a time interval. You can compare one force with another, but you cannot compare a force with a displacement. One way to look at this question is to ask a second question: Do we have any means to compare one mass with another? Mass"what does a weighing machine measure our weight or mass?" is the quantity of matter, the amount of "stuff" in the material. That "stuff" includes electrons, protons, and neutrons, each of which contribute a little bit of "stuff." The obvious answer is no, we cannot compare masses. We cannot count the number of protons, the number of neutrons, and the number of electrons in on body to compare with those in another body. When we talk about weighing something, we are determining its weight, which is a force. It is important that we keep in mind that weight is a force, the force of gravity on the body. As I mentioned in the earlier comment on this topic, there are basically two types of scales, the common term for a weighing machine. There is the beam balance type, where a known weight is moved along a beam in order to balance the beam and create an equilibrium situation. There is also the spring scale in which an elastic member is deformed, and the amount of deformation is an indication of the weight applied. When we weigh something, we are comparing forces and the torques developed by those forces. We say the forces are equal when we have established an equilibrium condition, and we can do this because this requires that the sum of forces be zero. In the beam type balance, we put an unknown weight in the pan, and then adjust the known weight so that the upward force through the mechanism is equal to the weight; this is the required equilibrium condition. All of this is a matter of comparing forces. In the spring type scale (including the modern electronic read-out strain gage based scales), we are deforming a spring in order to support the weight of the test object. The measure of that deformation (a displacement) is taken as the measure of the weight. This is true wither the displacement is many millimeters (as in the common fish scale) or only a few thousandths of a millimeter as in a strain gage scale. To go one step further, consider the following thought experiment. Imagine a scale (or either type) under a low shed roof. Now, put an empty balloon on the scale and weigh it. It will weigh very little, even if it is a rather large balloon. Next step, begin to inflate the balloon. For a while, as the balloon swells, you will only see a tiny increase in weight due to the weight of the air enclosed, but keep going. Eventually, the balloon will begin to bear against the shed roof, so that with increased air pressure, the balloon pushes up against the roof and down against the weight pan. After contacting the shed roof, the addition of even a small amount of air to the balloon will show a marked increase in indicated weight. Does this mean that the last little bit of air you added was much heavier than that previously pumped in? No, the last bit was just like the first part. It means that your scale is no longer indicating weight (gravitational attraction), but is showing the effect of the pressure loading from the internal pressure of the balloon. Add a little bit more air, and you will see a significant increase in indicated weight, but again, this is not truly weight but the force of air pressure. Even at this advanced stage in the process, the actual mass of the balloon and the air contained are very small, but the indicated weight is quite large. This is because it is no longer showing weight, but the force of the applied air pressure. The point of the thought experiment is to show that it is downward force that is read by the scale, not mass sitting in the pan. The answer to the original question is, "the scale measures weight (a force), not mass." DrD
  9. For starters, we might consider just what sort of "weighing machine" you have in mind. There are basically two types: 1) the beam balance, where the position of a sliding block is adjusted to the point where the moments on the beam are in equilibrium; 2) the force cell (usually a strain gage device) that is actually a spring scale with a very stiff spring. Either of these can be calibrated in either force or mass units, but they operate on different principles (or do they?), so do they measure the same quantity? DrD
  10. alright but you know if we stand on the weighing machine, we affected with the gravitational force and gravitational force pulls us at that time. so don't you think it will be our mass as well as gravitational force? which will lead to our weight.
  11. Mass. Because the machines are (by law) annually calibrated by standard mass that was kept by Government Metrology Bureau. There are no such thing as standard weight.
  12. what does a weighing machine measure our weight or mass?
  13. hey, guys!!! attempt the previous quiz. I will come up with the new quiz soon.
  14. Several weeks ago, I posted a kinematics problem over at Mechanics Corner (The Rocket Problem). It posed a simple single degree of freedom engineering problem that was largely kinematics in content. I asked readers to solve it, and send me their answers. Out of the thousands of readers on ME Forums, I have received exactly 2 solutions. From the 48 members of the Kinematics of Machines Club, I have not received any solutions at all. This was an elementary problem, a very simple undergraduate homework problem. Is this a poor response, or what? So I have to ask, are you guys really interested in kinematics? Do you ever actually do kinematics, or do you simply talk about it? What's going on here? Maybe I have it all wrong, and you are just too busy with much more sophisticated problems to be interested in such trivia. Perhaps a problem, such as the The Rocket Problem, is just beneath your notice! This may just be the case, but I don't think so. I'm looking for another explanation. Somebody step forward and tell me why no one is willing to participate. Speak up! Nobody is going to cut your head off, so don't be afraid. Just say why none of you are willing to contribute to the discussion. I especially invite our leader, the owner of this Club, to speak up on this issue. DrD
  15. hi, everyone! hope you all are doing well. guys i would like to encourage you all to post your doubts and help others. you can also provide some new researches and information about kinematics of machines. this is your group and you all are of part of it. thank you
  16. As I see this club (Kinematics of Machines Club) sit here and do nothing, I am reminded of other clubs from long ago. When I was a small boy, long, long ago, clubs were very popular. The typical "club" would start when several guys would build a "club house" in someone's yard. It was usually just a lean-to type structure, often a roof and one wall up against a garage wall or a fence, but it was to the center of all our activities. We would usually work feverishly for the better part of a day building the "club house." The wall and roof might very well be cardboard, a few tree branches, maybe a piece of corrugated sheet metal. We put a lot of ingenuity and effort into building our club house! Once it was finished, the big question always came up: What are we going to do now?? Sometimes, it would be proposed that our purpose was to fight other gangs in town. The biggest problem with that was, there were no other gangs that we knew about, so who could we fight? Along with that, there was always the risk that we might get hurt, perhaps even loose the whole fight and get beat up. Most of us were rather risk adverse! So, what were we going to do now? The only unifying thought that always came up was this one: We were going to keep the girls out (remember, this is a group of boys, roughly 6 to 10 years old!). Keeping girls out was obviously a priority, but we usually thought that an exception should be made if anyone's mother wanted to come in. Remember, mothers are not girls, even if there is some similarity, or so a group of small boys would reason. The whole thing would usually end when the father of the home where the club house was built would say something like, "I want this mess cleared away by the end of the day on Saturday." A few of us would dismantle the club house and pile it with the trash to be carried away while other members of the club simply vanished. With all the current activity in the Kinematics of Machines Club, and with its evident lack of purpose, I think I see a lot of parallel with the clubs of my childhood. The question in my mind now is, "When will we get the order to clear this mess away?" DrD
  17. Is this club going anywhere? Where is out leader, the club owner? What does he do if not provide leadership and direction? I ask again, is this club going anywhere? DrD
  18. When you ask about IT, I presume that is the same IT I spoke about when I wrote "Where would you publish IT"? Is that what you had in mind? For the blog post, I had not particular thing in mind, but most probably a technical paper presenting some sort of engineering solution. It could also be a book, but for that, it is a bit easier to locate a publisher. DrD
  19. Over at Mechanics Corner, there is a new problem posted involving a rocket on a launcher. This is made to order for folks interested in Kinematics of Machines, so be sure to go read the post and solve the problem. DrD
  20. I would like to encourage all members to read my latest blog post over at Mechanics Corner. The title is Where Would You Publish It? Check it out!! DrD
  21. Now you can take the quiz. Sorry for the inconvenience. It was a technical error. And you Always looked smater.
  22. Quiz author has to click button .. "Allow playing" .. this is because ..he has added 7 questions and the quiz is not ready -- may be he is adding 3 more questions... once he click on allow playing.... the quiz be open for every one .... And I can see - he has added quiz but nit added any questions......

  • Create New...