...Module 1 Force And Friction A force is a push or pull upon an object resulting from the object's interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of them. When the interaction ceases, the two objects no longer experience the force. Forces only exist as a result of an interaction. Force is a quantity which is measured using the standard metric unit known as the Newton. [pic] For simplicity sake, all forces (interactions) between objects can be placed into two broad categories: • contact forces, and • forces resulting from action-at-a-distance Contact forces are those types of forces which result when the two interacting objects are perceived to be physically contacting each other. Examples of contact forces include frictional forces, tensional forces, normal forces, air resistance forces, and applied forces. Action-at-a-distance forces are those types of forces which result even when the two interacting objects are not in physical contact with each other, yet are able to exert a push or pull despite their physical separation. Examples of action-at-a-distance forces include gravitational forces. For example, the sun and planets exert a gravitational pull on each other despite their large spatial separation. Even when your feet leave the earth and you are no longer in physical contact with the earth, there is a gravitational pull between you and the Earth. Electric...
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...Coefficient of Kinetic Friction and Surface Area Purpose To investigate the coefficient of friction with respect to surface area and the applied force in contact with the sliding force. Subject/Grade Level Physics/Grades 10-12 Questions to Probe Will increasing the load (FN) effect the kinetic friction (Fk)? Will increasing or decreasing the surface area of contact effect the kinetic friction? Concept Friction arises from the electromagnetic interaction between atoms of any bulk state of matter; solid, liquid, or a gas. When the surfaces of two objects are in contact, molecules on the surface of one object are attracted to molecules of the other object. Objects that may appear very smooth to us like a table top, however, on the molecular level have many peaks and valleys. When the surface of one of the object begins to move we call this interaction kinetic friction or sliding friction. Static friction is the friction when both objects are at rest. Sliding friction is less than static friction because when both objects are at rest the molecules have time to press together in the peaks and valleys. Sunshine State Standards (SC.C.2.3) The student understands that the types of force that act on an object and the effect of that force can be described, measured and predicted. (SC.H.3.3) The student understands that science, technology, and society are interwoven and interdependent. Materials 3 wood blocks 25cm in length force scale (spring scale) screw...
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...41 Manhole Flotation Introduction The proper functioning of a sewer system is dependent to a large degree on the performance of its appurtenances, and especially its manholes. As with many buried structures, the proper design of manholes should take into account the effect of the water table and its specific effect on installation and operating conditions. Figure 1 Manhole Installations Cross Section of Extended Base Manhole Installation The Buoyancy Concept From a fluid dynamics standpoint, the buoyant force acting on a submerged object is equal to the weight of fluid which that object displaces. In the case of a buried structure or manhole, this concept is applicable when a high ground water table or other subaqueous condition exists. As with the design of buried pipe, flotation should be checked when conditions such as the use of flooding to consolidate backfill, flood planes or future man-made drainage changes are anticipated. Extended Base Cross Section of Smoothwall Manhole Installation Manhole Buoyancy Analysis Vertical manhole structures of two types (Figure 1) are generally constructed, and each type should be considered when analyzing the flotation potential. The first case to be considered is a structure in which the base does not extend past the walls of the manhole. This structure will be called a smooth-wall manhole installation. Smooth-wall manholes utilize the weight of the structure itself and the downward frictional resistance of the soil surrounding...
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...Friction is what happens when any two things rub against each other. These can be solid things, like your two hands rubbing together, or your skis rubbing on the snow, or a hammer hitting a nail, or they can be gases, like friction with the air slowing down your car, or liquids, like friction with the water slowing down a boat. Nobody completely understands what causes friction. Partly, friction happens when the rough edges of one object snag on the rough edges of another object, and some of the objects' energy has to be used to break off those rough edges so the objects can keep moving. And when you rub two soft things together, like your hands, sometimes they squish into each other and get in each other's way. But even completely smooth, hard things have some friction. This friction is the result of the molecules in both objects being attracted to each other. We know how to make more friction or less friction, and how to predict how much friction there will be. There's more friction when the two objects are pushed together harder. If you push your hands together, it's harder to rub them up and down. If you pull the brake lever harder, your bike will stop faster. Because gravity pulls harder on things with more mass, things with more mass have more friction and are harder to move - a cube of iron will be harder to move than a cube of wood. Two solid things usually have more friction than two liquid things, or one liquid thing and a solid - that's why you slip on a wet surface...
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...UNIT 2 FRICTION Structure 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Introduction Objectives Friction Types of Friction Laws of Dry Friction Static and Kinetic Friction Coefficient of Friction Angle of Repose Least Force Required to Drag a Body on a Rough Horizontal Plane Horizontal Force Required to Move the Body Screw and Nut Friction 2.10 Self-Locking Screws 2.11 Condition for Maximum Efficiency 2.12 Screw Jack 2.13 Pivot and Collar Friction 2.13.1 Flat Pivot 2.13.2 Conical Pivot 2.13.3 Collar Bearing 2.14 Clutch 2.15 Types of Clutches 2.15.1 Conical Clutch 2.15.2 Single Plate Clutch 2.15.3 Multi Plate Clutch 2.16 Journal Bearing 2.17 Rolling Friction 2.18 Ball and Roller Bearings 2.19 Summary 2.20 Key Words 2.21 Answers to SAQs 2.1 INTRODUCTION When a body moves or tends to move on another body, a force appears between the surfaces. This force is called force of friction and it acts opposite to the direction of motion. Its line of action is tangential to the contacting surfaces. The magnitude of this force depends on the roughness of surfaces. In engineering applications friction is desirable and undesirable. We can walk on the ground because of friction. Friction is useful in power transmission by belts. It is useful in appliances like brakes, bolts, screw jack, etc. It is undesirable in bearing and moving machine parts where it results in loss of energy and, thereby, reduces efficiency of the machine. In this unit, you will study screw jack, clutches and...
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...This is because as the air pushes out of the back end of the balloon it pushed the car forward in the opposite direction with the same amount of force. This project also uses both friction and momentum. These were both factors in the races, another factor in the race was weight because the heavier the car means the more force you would need to allow the car to move and give the balloon having the greater force. After, watching the other cars race to improve my car I could have made a better support for the balloon and blown the balloon up to its maximum mass or size giving the car the most. Finally, I believe this project was a good opportunity to see Newtons third law in action and what roles friction and momentum can play in this...
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...SRI SHANMUGHA COLLEGE OF ENGINEERING AND TECHNOLOGY Pullipalayam,Morur(P.O),Sankari(T.k),Salem(D.T). Two Mark Questions Unit I – Basics 1. What is meant by mechanics? Mechanics is a branch of physical science which deals with the study of a body or bodies such as machines and structures at rest or in motion subjected to external mechanical disturbances such as forces, moments etc. What is meant by Engineering mechanics? Application of the principles of science of mechanics to the practical engineering problems is known as Engineering Mechanics. State the different types of mechanics? Depending upon the nature of the body involved, Mechanics can be classified into two types * Mechanics of Solids * Mechanics of Fluids Define Statics The study of a body which is in motion is known as statics Define Dynamics. The study of a body which is in motion is known as dynamics. Define Kinematics. It is the branch of dynamics which deals with the relationship between displacement, velocity, acceleration and time of a given motion, without considering the forces that cause the motion. Define Kinetics It is the branch of dynamics which deals with the relationship between the forces acting on a body, the mass of the body and the motion of the body. What do you understand from the concept of “Law of dimensional homogeneity”? Law of dimensional homogeneity states that “basic equation representing physical phenomenon must be valid for all systems of units”. State Parallelogram law. It states that...
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...nitride and SAE52100 under dry sliding H. S. BENABDALLAH, R. J. BONESS Department of Mechanical Engineering, Royal Military College of Canada, PO Box 17000 Stn Forces, Kingston, Ontario, Canada, K7K 7B4 E-mail: benabdallah-h@rmc.ca The friction, wear and acoustic emission behaviour of various combinations of alumina, silicon nitride, and SAE52100 steel, operating under dry sliding conditions, was investigated. A designed ball-on-flat-disc type of tribometer was used to conduct these experiments. This apparatus, equipped with a force sensor, using silicon strain gauges, measured simultaneously the normal load and friction force. Both forces were used to determine the real-time value of the dynamic coefficient of friction. The AE signal arising from the interaction of the surfaces in dynamic contact was also detected and a data acquisition system was used to gather this signal as well as the outputs from the force sensor, at high frequency. The effects of test duration, sliding speed and normal load on the above mentioned tribological parameters were evaluated. The interest of this study further extended to assess the correlations that may exist between the integrated rms acoustic signal (AE) and the friction mechanisms, wear volume, friction work as well as the material removal power. Under the specific conditions of the present experiments, no consistent relation was found between the variations of AE and corresponding dynamic coefficient of friction (COF) as function of time. The...
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...STUDY OF SLOPE STABILITY IN LIGNITE MINES By Mamta Jaswal (090610122047) Nilay J. Patel (090610122029) Ashish D. Patel (090610122026) Satish B. Patel (090610122013) Supervised by: Prof. Rajesh Arora M. Tech. A project part-1 submitted to Gujarat Technological University In partial fulfilment of The Requirements for the Degree of Bachelor of Engineering In Mining Engineering October 2012 CERTIFICATE This is to certify that Ms. Mamta Jaswal of BE. Semester VII (Mining engineering) has completed her one full semester on project work Titled “STUDY OF SLOPE STABILITY IN LIGNITE MINES” Satisfactorily in partial fulfilment of requirement of Bachelor of Engineering In Mining Engineering, Gujarat Technology University, Ahmedabad in the year 2012. Date: / / 2012 Place: Palanpur Internal Guide Prof. V.J. Sharma Prof. Rajesh Arora Head of Department (Mining engineering) Seal of institute CERTIFICATE This is to certify that Mr. Nilay J. Patel of BE. Semester VII (Mining engineering) has completed his one full semester on project work Titled “STUDY OF SLOPE STABILITY IN LIGNITE MINES” Satisfactorily in...
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...To determine the coefficient of static friction between two surfaces Objective: To investigate the relationship between the mass of load and the length of spring and the coefficient of static friction between two surface. Part 1: The relationship between the mass of load and the length of spring Apparatus and materials: Retort stand, spring, Slotted masses 200g with hanger, Meter rule Setup: Procedure: 1. One of the end of the spring is hooked on the retort stand. 2. The hanger with a 20g slotted mass is hang at the other end of the spring. 3. The length l1 of the spring has been measured, mass m1 of the load are recorded. 4. The mass m1 is increase and corresponding length l1 of the spring has been measured. 5. Data of l1 and m1 is tabulated. 6. Graph of l1 against m1is plotted. Part 2: The coefficient of friction between two surfaces Apparatus and Materials: smooth plank as inclined plane, Retort stand, wooden blocks, Electronic balance, spring, Protractor, Pendulum bob, Thread, Plasticine. Setup: Theory: If the wooden block is being displaced down the inclined plane, the block will return to its original position when released because the net force up the plane exceeds the limiting friction down the plane. The downward displacement is being reduced gradually until a stage where the block stays stationary when released. At this point, the force up the plane equalized the limiting friction down the plane. If T is the tension...
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...* Export citation * PDF (228 K) * More options... Search Wear Volume 253, Issues 1–2, July 2002, Pages 9–16 CM2000 S.I. Wear and fatigue in rolling contact * Yoshitsugu Kimuraa, , , * Masami Sekizawab, * Akio Nitanaic * a Kagawa University, 1-1 Saiwai-cho, Takamatsu, Kagawa 760-8521, Japan * b NTN Corporation, 1578 Higashi-Kaizuka, Iwata, Shizuoka 438-8510, Japan * c Tamagawa University, 6-1-1 Tamagawa Gakuen, Machida, Tokyo 194-8610, Japan * http://dx.doi.org/10.1016/S0043-1648(02)00077-7, How to Cite or Link Using DOI * Permissions & Reprints Abstract Researches on wear and fatigue in rolling contact from a tribological viewpoint are introduced. Transmission of traction and accompanying microslip in the contact region play critical roles in these phenomena. First, a quantitative analysis of wear in rolling contact with microslip is introduced, and it is shown that a simplified microslip theory can explain its behavior. Second, a marked change in contact fatigue life with traction is demonstrated, and a theory is introduced which relates the fatigue life with cumulative shear strain in the subsurface. Keywords * Contact fatigue; * Microslip; * Rolling contact; * Wear 1. Introduction Reduction of wear and prevention of contact fatigue are important objectives of railway technology and of tribology as well. However, these two engineering fields have been developing as different worlds, and researchers...
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...University, Coimbatore) COIMBATORE – 641 004. FACULTY GUIDE CONTENTS CONTENT Page No ACKNOWLEDGEMENT SYNOPSIS LIST OF FIGURE CHAPTER 1. INTRODUCTION...........………………………...……..………………………........1 1. VIRTUAL INSTRUMENTATION 1 2. LabVIEW 2 3. PIN ON DISC INSTRUMENT 3 2. LITERATURE SURVEY……………………..…………………………..………….5 3. PROBLEM DEFINITION AND OBJECTIVE……………………………......…….8 3.1 PROBLEM DEFINITION 8 3.2 OBJECTIVE 8 4. METHODOLOGY………………………………………………………….………....9 5. PROCEDURE AND RESULTS…………………………………...…..……10 5.1 Calibrating the Pin on Disc Instrument 10 5.2 Conversion of Time to Sliding Distance 11 5.3 Exporting Values to Spreadsheet File 12 5.4 Steps to Run the Program 13 6. CONCLUSION………………..………………………………..….…….....…...…...15 BIBLIOGRAPHY..........................................................................................................16 ACKNOWLEDGEMENT We would like to express our sincere gratitude and profound thanks to Dr. R. Rudramoorthy, Principal, PSG College of...
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...PhysRozz Midterm 2012 1. Which is not a vector quantity? 1) electric charge 2) displacement 5. As the angle between two concurrent forces decreases, the magnitude of the force required to produce equilibrium 1) decreases 3) velocity [via06-07] 2) increases 3) remains the same 4) magnetic field strength 2. An astronaut standing on a platform on the Moon drops a hammer. If the hammer falls 6.0 meters vertically in 2.7 seconds, what is its acceleration? 6. A child walks 5.0 meters north, then 4.0 meters east, and finally 2.0 meters south. What is the magnitude of the resultant displacement of the child after the entire walk? 1) 4.4 m/s 2 2) 1.6 m/s 2 1) 1.0 m 2) 5.0 m 3) 2.2 m/s 2 4) 9.8 m/s 2 3) 3.0 m 4) 11.0 m 3. A 2.00-kilogram object weighs 19.6 newtons on Earth. If the acceleration due to gravity on Mars is 3.71 meters per second 2 , what is the object’s mass on Mars? 1) 2.64 kg 2) 2.00 kg 3) 19.6 N 7. The diagram above represents a spring hanging vertically that stretches 0.075 meter when a 5.0newton block is attached. The spring-block system is at rest in the position shown. 4) 7.42 N 4. A car moves with a constant speed in a clockwise direction around a circular path of radius r, as represented in the diagram above. The value of the spring constant is 1) 38 N/m When the car is in the position shown, its acceleration is directed toward the 1) south 2) east 3) west 2) 650...
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...Lab Assignment 4: Types of Force Instructor’s Overview In many physics problems involving Newton’s laws of motion, you’ll see statements like, “assume a frictionless surface” or “neglecting air resistance…” In this lab we will be exploring both friction and air resistance, two resistive forces that are critical in the design of real-world products and systems. Understanding the effects of these types of forces is essential in the design of such things as aircraft, automobiles, braking systems, and countless other objects. This activity is based on Lab 4 of the eScience Lab kit. Although you should read all of the content in Lab 4, we will be performing a targeted subset of the eScience experiments. Our lab consists of two main components. These components are described in detail in the eScience manual. Here is a quick overview: * In the first part of the lab, you will measure the force it takes to pull objects of different mass. This experiment focuses on the effects of frictional forces. (eScience Experiment 1) * In the second part of the lab, you will investigate the effects of air resistance by performing controlled drops of coffee filters. Notes: * Please follow the instructions in this document for the air resistance experiment. * Record all of your data in the tables that are provided in this document. Take detailed notes as you perform the experiment and fill out the sections below. This document serves as your lab report. Please...
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...blocks. c. Find the resultant force on each block. d. Find the magnitudes of the contact forces between the blocks. 2. A crate of weight Fg is pushed by a force on a horizontal floor as shown in the figure below. The coefficient of static friction is μs, and is directed at angle θ below the horizontal. e. Show that the minimum value of P that will move the crate is given by P=μsFgsecθ1-μstanθ f. Find the condition on θ in terms of μs for which motion of the crate is impossible for any value of P. (Use the following variable as necessary: μs.) 3. What horizontal force must be applied to a large block of mass M shown in the figure below so that the tan blocks remain stationary relative to M? Assume all surfaces and the pulley are frictionless. Notice that the force exerted by the string accelerates m2. (Use the following as necessary: m1, m2, M, and g.) 4. A crate of eggs is located in the middle of the flat bed of a pickup truck as the truck negotiates a curve in the flat road. The curve may be regarded as an arc of a circle of radius 30.5 m. If the coefficient of static friction between crate and truck is 0.650, how fast can the truck be moving without the crate sliding? 5. An object of mass m = 0.580 kg is suspended from the ceiling of an accelerating truck as in the figure below. Take a = 3.20m/s2. g. Find the angle θ that the string makes with the vertical. h. Find the tension T in the string. 6. The...
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