Physics Lab Report Centripetal Force Essays

Physics Lab Report Centripetal Force Essays Physics Lab Report Centripetal Force Paper Physics Lab Report Centripetal Force Paper Sketching of the set-up Theory Centripetal force F is the net force causing the centripetal acceleration of an object performing uniform circular motion. Its magnitude is given by the equation: = Mrs.. When an object is whirled in horizontal circular motion in mid-air with a piece of string (as shown in figure 1 above), the centripetal force on the object is provided by the horizontal component of tension in the string: 2 =>2 (since r = L) Procedure 1 A triple beam balance is used to find the mass of the rubber bung, the screw nuts and the wire hook respectively. The total weight of the screw nuts and the wire hook provided the tension T in the nylon thread. 2 The centripetal force apparatus is set up (Figure 2). The paper marker is used to set the length L of the nylon string between the rubber bung and the glass tube to 0. 2 m. 3 Hold the glass tube vertically and whirl the rubber bung around in a horizontal circle. Increase the speed of the rubber bung gradually until the paper marker is just below the lower end of the glass tube (Figure 3). 4 The time of 50 revolutions of the rubber bung is measured and record the exults. Calculate the angular velocity w of the rubber bung and the tension T in the nylon string. 5 The steps 1, 2 and 3 is repeated for several times with different lengths L (0. Mm, 0. Mm and 0. Mm) of the nylon string. The results are recorded and the mean tension T in the nylon string is calculated. 6 Compare the mean tension (2) found in circular motion and the weight of screw nuts and wire hook (MGM). Explain their difference (if any) briefly. It the two values are close to each other, it could be concluded that the equation for centripetal force is verified. We have, By y = mix + c, slope of the graph plotted The experimental value of Tension = 41. 5 x 0. 0155 = 0. 644 N, where the theoretical value of Tension = 0. 653 N It is noted that the experimental value of is slightly lower than the theoretical one due to the several sources of error made in the experiment. Percentage error = (0. 653 x Sources of error: 1 . There is friction existing between the string and the glass tube, and there is air resistance. Thus, the motion of the circulation may be affected and the measurement of angular velocity might not be accurate. Secondly, constant speed or constant angular velocity of the rubber bung may not be maintained during the whirling. Thus, the measurement of angular velocity might not be accurate. 3. The radius of the circular motion and thus the length of nylon string L cannot be kept constant throughout the circular motion because there may be a variance of the force applied to keep the paper marker on the level of glass tube. Thus, t he string and paper marker may move up and down and the accuracy of the tension T may be affected. 4. The stopwatch is controlled by human hands. Thus, the reaction time of human brain (around 0. As) may lead to inaccuracy and affect the measurement of time taken and hence the accuracy of angular velocity is affected. 5. There may be miscounting in the number of circulations, because the time for 50 revolutions is quite long and students may be distracted. The accuracy of the experimental results can be improved by the following suggestions: 1. The experiment was carried out with the range of L 0. Mm, 0. Mm, 0. Mm, 0. Mm. Further experiments can be carried out beyond this range to increase the accuracy.

The Long History of Perfume

The Long History of Perfume Perfume is thousands of years old, with evidence of the first perfumes dating back to Ancient Egypt, Mesopotamia and Cyprus. The English word perfume comes from the Latin per fume, meaning through smoke. History of Perfume Around the World The Ancient Egyptians were the first to incorporate perfume into their culture, followed by the ancient Chinese, Hindus, Israelites, Carthaginians, Arabs, Greeks, and Romans.   The oldest perfumes ever found were discovered by archeologists in Cyprus. They were more than four thousand years old. A cuneiform tablet from Mesopotamia, dating back more than three thousand years, identifies a woman named Tapputi as the first recorded perfume maker. But perfumes could also be found in India at the time. The earliest use of perfume bottles is Egyptian and dates to around 1000 BCE. The Egyptians invented glass and perfume bottles were one of the first common uses for glass. Persian and Arab chemists helped codify the production of perfume and its use spread throughout the world of classical antiquity. The rise of Christianity, however, saw a decline in the use of perfume for much of the Dark Ages. It was the Muslim world that kept the traditions of perfume alive during this time- and helped trigger its revival with the onset of international trade. The 16th century saw the popularity of perfume explode in France, especially among the upper classes and nobles. With help from â€Å"the perfume court,† the court of Louis XV, everything got perfumed: Furniture, gloves, and other clothing.   The 18th-century invention of eau de cologne helped the perfume industry continue to grow.   Uses of Perfume One of the oldest uses of perfume comes from the burning of incense and aromatic herbs for religious services, often the aromatic gums, frankincense and myrrh gathered from trees.  It did not take long, though, for people to discover perfume’s romantic potential and it was used both for seduction and as preparation for love-making. With the arrival of eau de cologne, 18th-century France began using perfume for a broad range of purposes. They used it in their bath water, in poultices and enemas, and consumed it in wine or drizzled on a sugar lump. Although niche perfume makers remain to cater to the very rich, perfumes today enjoy widespread use- and not just among women. The selling of perfume, however, is no longer just the purview of perfume makers. In the 20th century, clothing designers began marketing their own lines of scents, and almost any celebrity with a lifestyle brand can be found hawking a perfume with their name (if not smell) on it.