Friction Experiment: Design and Results

Friction Experiment: Design and Results EXPERIMENT 37 Friction I. Introduction Whatever action you do whether it is walking, driving, or when any two surfaces meet there is friction between them. Friction opposes the applied force to an object and opposes the motion of an object. In many of the labs in this course we try to minimize it or neglect it in the lab, but it is there. When we use the air track, the friction is dramatically reduced due to the air cushion under the air car so the car stays in motion for an extended period of time, but it still stops. Or in the case of an oscillating object, we ignore the slowing of the oscillation, but it still slows down and stops. The actual cause of friction is complex atomic interaction but, the simple idea of friction is atoms rubbing against each other, adsorbing energy from the motion. Friction is a force; it prevents an object from moving or changes the motion of an object. This lab will cover two types of friction, static friction and kinetic friction. Static friction is a force that resists motion so that the surfaces are not in motion relative to each other. The maximum amount of force applied to the block, at the instant before the block moves, is referred to as the maximum static friction force, f S Max. One example of this type of friction is walking. Once enough force is applied to the system to overcome the static friction force, it starts to move. When the block is moving against the surface, then the friction force is called the kinetic friction force, f k. Kinetic friction appears when the two surfaces are sliding relative to each other. One example of this type of friction is pushing a file cabinet across the floor. In this lab you will pull a weighted block across the table and measure the force it takes to start moving the block (just an instant before it moves) and while the block is moving across the table. The forces in this lab are many, the block exerts a force on the table, the table exerts a force on the block ( fN ). And the earth exerts a force on the block (mg) and the block exerts a force on the earth. This experiment will consider the room and table as stationary objects and therefore having no accelerating force on them, then the net force on the stationary block is fnet = 0 (1). The force of the block on the table is equal to the force of the block on the earth, weight or mg, mg fN = fNet (2) thus mg = fN (3). Figure 1: Diagram of two blocks one stationary and one moving. The stationary object is held back by static fraction, while the moving object is acted on by friction and a  pulling force. The static friction force acts equal and opposite to the pulling force, as the pulling force increases the static friction force increases, resulting in no motion. Sometimes the pulling force will increases and it will exceed the static friction and the block will begin to move. The point of maximum force is called maximum static force, f SMax. An observation about static friction is that maximum static friction f SMax is proportional to the normal force, fN, through a constant  µs, f SMax =  µs fN. (4) The  µs term is referred to as the coefficient of static friction. This means as the normal force ( fN ) increases, the maximum force needed to move the block increases in a proportional amount. The coefficient of static friction is dependent on the two surfaces in contact so different surfaces will have different coefficients of friction. A second observation about friction is that friction is independent of the size of the contact area between the two solid surfaces, which means the same force spread over different areas still would have the same force of friction. Kinetic friction like static friction is a retarding force exerted on a sliding object in contact with a surface. When the object is sliding with a constant velocity the force of friction is equal to the pulling force. It follows the same equation as static friction but the relationship between kinetic friction and the normal force has a different coefficient. The coefficient is referred to as the kinetic coefficient of friction  µk. fk =  µk fN. (5) Kinetic friction also does not change when the surface area of the two surfaces changes. You will be measuring both static and kinetic friction forces in this lab and you should find that the kinetic friction is usually lower that the maximum static friction. II. Equipment and Procedure IIa. Equipment: Force sensor, block, motion sensor, laptop PC, 750 interface, friction surface aka table, string, pulley, weights and weight hanger. Figure 2: Equipment setup of the friction experiment. The hanging mass will pull the force sensor with a mass, while the motion sensor will measure the displacement of the force sensor. Once the hanging mass force exceeds the friction force, the force sensor will move, and the motion sensor will measure the displacement. The moving force sensor will have a velocity measured by the computer, and the net force on the force sensor will be measured. IIb. Procedure: The mass of the block and force sensor needs to be measured so that the total mass of the block/force sensor on the table can be determined. Hook the motion sensor and the force sensor to the 750 interface box and hook the interface box to the laptop. The force sensor is measuring the force exerted on the block while the motion sensor will measure the change in distance of the block. Turn on the computer and 750 interface, start the Data Studio program and create an experiment. Select a digital port and add the motion sensor to the experiment. Double click on the motion sensor to open the settings of the motion sensor, set the frequency rate to 25 Hz and close the window. Drag the motion sensor icon in the upper left to the graph icon in the lower left. Go to an analog port on the 750 interface box and add the force sensor to the experiment, double click on the force sensor to open the sensor settings, set the frequency to a minimum of 500 Hz. Drag the force sensor icon in the upper left to the lower left graph icon. One reminder is to hit the tare button every time before you run an experiment. This action resets the for ce sensor to zero Newtons before each run. Static Friction Experiment: part one Start the experiment, tare the force sensor. Add the hanger and add weight incrementally. As you try more runs use smaller masses for your increment. Keep adding weight until the block starts to move. Once the mass moves, stop the experiment. Repeat the experiment 6 times to get an average value and perform standard deviation (SD) on your values. Kinetic Friction Experiment: part two Start the experiment, tare the force sensor. Pull the force sensor using the string to make the block move. Once the block is moving at a constant velocity, this will indicate what force is needed to match the kinetic friction. Plot the displacement vs. time from the motion sensor. Fit the curve to a linear function to show that the block has a uniform velocity. Repeat the experiment 6 times to get an average value and perform SD error analysis. Kinetic Friction Experiment: part three Start the experiment and tare the force sensor. Add the mass required to move the block with 100 grams extra. The block will start to move with an accelerating velocity, if not add an extra 50 grams until it does. The plot of the position vs. time will determine if the block is accelerating. Question: What should the plot look like if the block is accelerating? Once a run is complete with the block accelerating along the table, stop the experiment. Plot the displacement vs. time from the motion sensor. Fit the curve to a quadratic function to find the acceleration of the block. Repeat the experiment 6 times to get an average value and perform SD error analysis. III. Data The graph of the force vs. time or determines the maximum value of the force. The maximum force is the static friction force. In part two (kinetic friction), drag the block at a uniform velocity. The plot of time vs. displacement will clearly identify the linear motion. Use a linear formula to fit the curve if necessary. Measure the force on the block when it is moving. In part three (kinetic friction), drag the block with an accelerating force and generate a plot time vs. displacement in a graph. Fit the curve to a quadratic formula and determine the acceleration of the block. The acceleration of the block is used to determine the net force on the block. The net force on the block is the difference between the force of the mass hanging down and the force of friction holding it back. One reminder is the displacement of a moving object is related to the acceleration through equation (6). = (6) IV. Results Calculate the coefficient of static friction of the block, from the force exerted on the block and the mass and force of the block on the table. Calculate the SD from the values obtained in the experiment. Calculate the kinetic friction force from the two different methods. First: calculate the kinetic friction from the constant velocity of the moving block. The force need to move the block at a constant velocity is equal to the kinetic friction force. Calculate the SD from the values obtained in the experiment. Second: calculate the kinetic friction difference from the accelerating block from the hanging force and the resultant force on the block. The mass of the block is known and the acceleration of the block is measured from the curve fit. The net force on the block can then be determined. The hanging force is known from mass times gravity (mg) and from that the force of kinetic friction can be calculated. V. Discussion What are values of the static and kinetic friction? Are the two values of kinetic friction similar? Are the kinetic friction values within the standard deviation? What happens when a sliding object has the pulling force reduced below the kinetic fiction force? How much force will it take to get it moving again? Is there a there large distribution in the values of static and kinetic friction? If so why? What would happen to the value of friction if the mass of the block is doubled? Is a wheel rolling, static or kinetic friction? Why can’t static friction be less that kinetic friction? Discuss the implication of this.

Three day road summary

The story opens in 1919 after the war and we are first introduces to an old woman named Nicks, a native American living in Canadian we learn she is a medicine woman and healer. She's one of the last of her clan to live in the bush, having fought off going to the reserves and governments wanting to take the Indian out of the Indian at the time. She hears that her nephew whoso been sent off to the war has returned and paddles a long way to get to the train station.She sees Just how much the war has left him damaged: he's lost a leg and Is addicted to morphine, which was the pain medicine was used at the time. She understands that he's actually close to death and as she paddles him home, she realizes that In order to help him all she has to offer are the stones of her life. While she does this, Xavier who can't even talk and almost deaf Internally reflects on the past number of years, on his experience In the war with his childhood friend Elijah.This gives way to two different stories, two different narrators Nicks and Xavier. The novel Is structured Like one of those Russian Matrons dolls, the ones where you open up the doll to find other, smaller dolls inside. Nicks tells Xavier stories of her life, Elijah is obsessively compelled to tell Xavier war stories and poor Xavier is too damaged to speak of his own stories and so relives them in his morphine-addled head. One of the many ironies is that the skills of the two friends used for hunting in the bush become incredibly valuable on the battle field.The army quickly realizes their skill as trackers and as marksmen and so they are made into snipers quite quickly once they reach the front. Although their killing-abilities are remarkably respected and quite well regarded by the rest of the regiment, they still face racism within the army as a consequence of who they are. The characters feel very much like they eave to prove themselves as they face prejudice. Elijah discovers a lust for killing and is encouraged by s ome French soldiers to retrieve the scalps of his victims to prove he's killed as many as he claims.He treats the war as a game wanting to be the one to hold the most kills, while Xavier tries to come to terms with his devastating war-experiences. Elijah In his madness becomes a virtual killing machine, a winding In native terms. The welding Is a two sided thing: legend goes that If a person eats another human being In times of great starvation then he will grow to great heights and have an Insatiable appetite. The notion has a psychological aspect too: moral boundaries are hard to set when In the trenches and some Like Elijah get carried away by It all to a point of no return.Three day road summary By floral Indian at the time. She hears that her nephew who's been sent off to the war has the war has left him damaged: he's lost a leg and is addicted to morphine, which was death and as she paddles him home, she realizes that in order to help him all she has to offer are the stories o f her life. While she does this, Xavier who can't even talk and almost deaf internally reflects on the past number of years, on his experience in he war with his childhood friend Elijah.

Gd/Pi Topics

?i every1, these are some the topics for oral presentation at ALLIANCE on 9 July– 1. Talent management is critical in company success. 2. Global warming. 3. Global markets. 4. Online social networking. 5. World is flat. 6. Controversial advertisements should be banned. 7. Employee relationship management. 8. Research and its importance. 9. Right to information act, citizen’s charter. ?1. EFFECTS OF SOCIAL NETWORKING ON YOUTH 1. To survive in the civilized world one definitely needs to be a hypocrite. 2. Do nice guys finish last. 3. Importance of Internet. . Should New Delhi be the Capital of India. 5. Should women engage in Defence Services. 6. There is no right way of doing the wrong thing. 7. Is god male. 8. How is censorship in movies protecting our culture. 9. Crime and Violence should not be shown on Television 10. Classical musical is our Heritage. 11. Cleanliness is a fundamental responsibility. ?1. Talent management is critical in company success. 2. Global warm ing. 3. Global markets. 4. Online social networking. 5. World is flat. 6. Controversial advertisements should be banned. 7. Employee relationship management. 8. Research and its importance. 9. Right to information act, citizen’s charter ?GD/PI Topics:- 1. Remix in music in today’s world a good trend 2. Are primary schools more important than management schools? 3. Should Advertising be banned? 4. Let sleeping dogs lie. 5. Individual Freedom. 6. Is social networking good/bad? , etc 7. separation of state, socialism 8. food first, ethics later 9. It was whether India should spend its resources at space research when its a resource deficient country 10. IS CONSUMER REALLY A KING IN INDIA 1. ‘Advertising Cheats people. Hence, should be banned' 12. Who says MNCs are superior to Indian companies ?Other micro presentations (from Christ Uni) 1 Aadhaar 39 Local community in tourism 2 Airline Business in India 40 Managing Stress at Workplace 3 Anti Corruption Bill 41 Micro finance in Tourism 4 Arab Spring 42 Mind Control 5 ASSOCHAM 43 Mobile Phones 2020 6 Biofuel 44 Molecular Gastronomy 7 Brand IPL 45 National Telecom Policy-India 8 Capital Markets 46 Neuromarketing 9 Celebrity Advertising 47 Non Proliferation Treaty 10 Climate Change 48 NREGS 1 Cognitive Computing 49 Organic Farming 12 Community Radio 50 Personal Aerial Vehicle (PAV) 13 Community Tourism 51 Promise of Nanotechnology 14 Consumer Protection 52 Psycho-Kinesis 15 Convenience Food 53 Public Private Partnerships 16 Couch Potato Generation 54 Quantum Levitation Technology 17 Creative Entrepreneurship 55 Responsible Tourism 18 Cross Cultural Communication 56 Right to Information 19 Cultural Tourism 57 Roles of Trade Unions Today 20 Cyber-Psychology 58 Rural Tourism 21 Digital Marketing 59 Security Laws in India 2 Emotional Quotient 60 Social Accounting 23 Ethics in Business 61 Speech Recognition Technology 24 Fashion Brands 62 Spiritual Tourism 25 FDI Vs Trade in India 63 Sustainable Energy 26 Food Crop Cultivation in India 64 Tourism and Regional development 27 Formula one in India 65 Tourism and Cultural Unders tanding 28 Fringe Benefits in Corporate 66 Tourism for Heritage Conservation 29 Future of Personal Computers 67 Tourism vehicles for communal harmony 30 Global Village 68 Unconscious Motives 31 Harry Potter 69 UNESCO India 32 Holistic Nutrition 70 Value Education – Why?

The Evolution of a Horse Essay - 924 Words

The Evolution of a Horse Throughout history, humans have depended on the horse. Horses have contributed to the growth of humankind as transportation, farm workers, and battle steeds. They have been trained to support humans in many ways. When did this relationship begin? At what point did the horse become a vital part of human society? Exploring the evolution of the horse can help to answer these questions. A mammal with hooves that have an odd number of toes on the rear feet are known as odd-toed ungulates. The middle toe on each rear hoof is usually larger than the ones next to them. Horses are members of the odd-toed ungulates which includes the horses, tapirs, and rhinoceroses. They are relatively large grazing animals with†¦show more content†¦Four of the toes had early proto-hooves. The back legs had small hooves on three of the five toes. The toes were padded like a dog’s toes. The Hyracotherium had three incisors, one canine, four premolars, and thr ee grinding molars on each jaw, which was a typical tooth structure of early mammals who were omnivorous browsers (Hunt 4). Eohippus survived for about twenty million years with relatively few evolutionary changes (Wikipedia 7). These animals lived in a sub-tropical climate and ate soft fruits and the leaves of trees. During the middle to late Eocene and into the Oligocene epoch several other members of the equids, with distinct evolutionary changes, existed including the Orohippus, Epihippus, Mesohippus, and Miohippus. The Orohippus developed from the Hyracotherium and shared many of the same traits. One major change was that the first and second toes disappeared. Another significant change occurred in the teeth. The last premolar changed to become like a grinding molar. Also the crests were more defined showing that the Orohippus’s diet had changed to a tougher plant material. 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