D2 Measurong Youngs modulus of copper Essays

D2 Measurong Youngs modulus of copper Essays D2 Measurong Youngs modulus of copper Paper D2 Measurong Youngs modulus of copper Paper In this experiment, The Youngs modulus of copper will be mesured . Apparatus copper wire 4m G-clamp polley on clamp -2*Wooden block 2*rule (half meter and meter rule) slotted mass with hanger 15 Â  0. 1 kg adhesive label -micrometer screw gauge -safety goggles -polystyrene board (Warning : Wear safety goggles when doing this experiment ) Theory When a spring is stretched or compressed by a force. The extension is directly proportional to the applied force. This relationship known as Hookes law. Force=ke. However,the law is used when the proportional limit is not exceeded. To further investigate how the material behaves when it is stressed,we define: The stress applied to the wire is defined as the force applied per unit cross-sectional area. Stress = force per unit area =F/A (where F is the force or tension in the wire, A is the cross-sectional area) When the wire being stretched,it is under strain. The strain is defined as the extension per unit length. Strain = extension per unit length = e/l (where e is the extension and l is the unstretched length of the wire) Withon the proportional limit,the ration stress/strain is a constant whose value depends on the material of the wire. It is known as the Young modulus of the material E = stress/strain = (F/A)/(e/l) = Fl/Ae From this law,a material with larger Youngs modulus means a greater stress is required to produce the same strain than another material with smaller Youngs modulus gives how stiff a material is. In this experiment, we will hang different loads (m) to one end of a copper wire of length l and diameter d. The extension (e) for each load is measured. From the slope of the straight part of the m-e graph, Youngs modulus of copper can be found. Since F=mg and A= cross-sectional area of the wire = ? (d/2)2 = ? d2/4, Youngs modulus of the copper wire is given by E = Fl/Ae = mgl/(? d2/4)e = m/e x 4gl/? d2 = slope of graph x 4gl/? d2 Procedure 1. To measure the diameter of the wire at two end and the center of the wire by using a micrometer screw gauge to take the mean value of the diameter. 2. The apparatus is seted on the bench as shown in Fig. D2. 1. 3. Fix an adhesive label on the copper wire as a marker 4. Measure the unstretched original length of the wire before addong slotted mass to the wire (from the wooden blocks to the slotted mass) 5. The copper was loaded in steps and the extension produced was recorded. Steps were continued until the wire broke Results 1st measurement 2nd measurement 3rd measurement . 2 1. 3 1. 4 0. 0042 0. 005 0. 007 0. 009 0. 015 0. 036 0. 087 0. 155 Before the load increase to 0. 7 kg. The extension is nearly proportional to the force . Also stress is nearly proprtional to strain. After the load is beyond 0. 7kg,extension is not proportional to force and stree is not proportional to strain. The plastic deformation occur. The wire does not return completely to its original length . The wire broke whn the load is increase to 1. 4 kg. This part of graph obeys Hookes law. Fig. 4 % strain = extension / original length x 100% = 0. 0042/ 3. 95x 100% = 0. 106% Fig. 4 shows the best straight line through the points of the straight part of the graph. Slope of load-extension graph = 189. 72 kgm-1 Youngs modulus of copper E = slope of graph x 4gl/? d2 =189. 72 x 4(10)(3. 95)/? (0. 000278)2 =123. 46109 Pa Error estimation Sraw lines of maximum and minimum slope through the points of the graph. Find the slope and take the large deviation from the slope of the fitted graph as the error Maximum slope = 208. 77 Minimum slope = 163. 15 Error in slope = i 26. 57 % error in slope =14.00 % Estimate the possible errors in l and d and express them as percentages Error in l = 0. 1cm/2 = i 0. 05cm % error in l =0. 0127% Error in d = i 0. 005mm %error in d = 0. 0180% Hence, estimate the % error in E. % error in E = % error in slope + % error in l + 2 i % error in d = 14. 00% + 0. 0127% + 2 i 0. 0180% = 14. 049% Error in E = i 1. 7345i 1012 Discussion From the graph of Fig. 4 . The wire is undergo a proportional limit before the load increase to 0. 7 kg. Its obeys Hookes law. When the load is not reach to a yield point. The wire can returns to its original length when the load is removed. In this graph . The slope of the graph of load against extension determines the Youngs modulus. When the load is beyond the yield point. The plastic deformation will occur. The wire does not return completely to its original length . It will contain a permanent extension. Then the load is added to the wire continuously. The extension of the wire is more signifiance.. The wire narrows uniformly. In our experiment,The maximum stress at the breaking point. Break is due to the wire narrows unevenly to form necks. There are some precautions for this experiment. When we read the value of the length of the wire. It is more accuracy as we observe the value vertically. Moreover,when the load is add on the wire. It is more suitable to add slowly. This can avoid the force added by our hand. Besides,students should wear safety goggles when doing this experiment. It can protect our eye is hited by the wire. Youngs modulus is more useful than force constant because the Youngs modulus depend on the force per unit cross sectional area. Also,the extension is per unit length. It is more accuracy than the force constant which is only depend on the relationship between the force and extension. From the book called NEW WAY PHYSICS. the youngs modulus of the copper is 124109 Pa. Also from answers. com/topic/young-s-modulus. the Youngs modulus is between110 to 130 x109 Pa. Compare with our result. It is 124109 Pa. The answer is very close to the reference answer. It is because we take all of the value very carefullyand seriously for decrease the error. Conclusion The Youngs modulus is depend on the materials. The Young modulus of copper which measure by our group is 124109 Pa.

Names of Animals and Insects Formed by Folk Etymology

Names of Animals and Insects Formed by Folk Etymology Names of Animals and Insects Formed by Folk Etymology Names of Animals and Insects Formed by Folk Etymology By Mark Nichol This post lists words derived from words in other languages as a result of folk etymology, a process by which speakers adopt the foreign terms after revising them by using existing elements from their native language. bumblebee: This word stems from the Middle English word humbul-be, but by association with bombeln, meaning â€Å"boom† or â€Å"buzz,† the initial sound changed. caterpillar: The word for a butterfly or moth larva stems from the Old French word catepelose (â€Å"hairy cat†); the alteration of the third and fourth syllables to -pillar (from Middle English piller, meaning â€Å"plunderer†) may have developed from the notion of its destructive effect on plants. cockroach: This word is derived from the Spanish term cucaracha and employs two words that, when combined, sound similar to the original word. cockatoo: This bird’s name is from the Malay word kakatua by way of the Dutch term kaketoe. crawfish/crayfish: Although these are variations of a name for an aquatic animal, the second syllable in each is not equivalent to the word fish; the entire word, ultimately from a Germanic language, stems from the Anglo-French term creveis by way of the Middle English word crevis and is related to crab (and perhaps to carve). geoduck: This name for a Pacific Northwest clam, which comes from a local Native American term, has nothing to do with ducks- or with the Latin prefix geo-, meaning â€Å"earth†; also, the spelling of the first two syllables is inexplicable, since they are pronounced like gooey. greyhound: The first syllable of this word does not refer to the dogs color; it is from the Old English term grieg, referring to a female dog. lapwing: This word for a species of bird started out as the Old English term hlÄ“apewince (â€Å"leap wink†), inspired by the bird’s flapping mode of flight. mandrill: This word for a type of baboon derived from attempts of English speakers to pronounce the name of the animal in an African language. mongoose: The animal’s name stems from mamgusa in Prakrit, an Indic language. (It has nothing to do with geese, so the plural is mongooses.) muskrat: This animal is a rodent, but its name is not derived from its scent or its kinship with rats; the word from which it derives is of Algonquian origin. peacock/peahen/peafowl: The first syllable of these words comes from pavo, the Latin (and Spanish) name for it. Peafowl is redundant, while peacock and peahen denote the male and female of the species. polecat: The first syllable of this name for a mammal in the weasel family (also an alternative name for the polecat’s relative, the skunk) is derived from the French term poul (the base of poultry), from its barnyard depredations. popinjay: This older term for a parrot, now exclusively applied to an arrogant person, is ultimately from the Arabic word babghÄ . quahog: This word for a type of clam stems from poquauhock, from the Narragansett language, and has no relation to pork. sockeye: The name for a type of salmon does not refer to its eyes; it originates from an attempt to pronounce a Native American word for the fish. wheatear: This thrush was originally called a wheatears; that name is a euphemism for â€Å"white arse,† a reference to its light-colored rump. white rhinoceros: White, in the name of this animal, is not a reference to its color; it stems from the Afrikaans adjective weit, meaning â€Å"wide,† a description that distinguishes its wide upper lip from the pointed lip of the black rhinoceros. woodchuck: This alternative name for the groundhog derives from the assignment of two English words whose sounds resemble those of a Cree word. Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Vocabulary category, check our popular posts, or choose a related post below:Homograph ExamplesAmong vs. AmongstComma Before Too?