2450485 1997 Feb 05 14:22 pha-rfuller.unl.edu 129.93.34.51 student: Testor Tom keywords: search word here # hits: hit # docs: doc 2d ref: 2 d selection here free body ref: free body diagram here summary 2d motion: summary 2 d summary free body: summary free 2450486 1997 Feb 06 13:48 xyp29p20.ltec.net 204.96.104.30 student: Jason Henning keywords: Free Body Diagram & Two Dimensional Dynamics & Kinematics # hits: 208 # docs: 76 2d ref: Conceptual Based Text Citation: Spears, J. D., and Zollman, D. "The Fascination of Physics." (The Benjamin/Cummings Publishing Company, Inc. 1985.) Velocity In the 1929 Rose Bowl, a Georgia Tech halfback fumbled. Roy Riegels, the California center, scooped up the loose ball and dashed toward the goal line. Faster than the other players, he neared the goal line virtually untouched. Suddenly, his teammate tackled him - it was the wrong goal! "Wrong Way" Riegels had the right speed but the wrong velocity. Velocity is defined as the ratio of the displacement of an object to the time interval required for the displacement. velocity = displacement / time Speed and velocity are related to each other in the same way that distance and displacement are related. As an example, consider "Wrong Way" Riegels' infamous run. His path is shown in Figure 2-2. The distance he traveled was 67 yards (yd), while his displacement was 55 yd, wrong way. We estimate that his run took about 15 s. Using this information, we can compare his speed and velocity. Riegels' speed was 67 yd divided by 15 s, which equals 4.47 yd/s. By contrast, his velocity was 55 yd, wrong way, divided by 15 s, or 3.67 yd/s, wrong way. Riegel probably had good speed for a center in 1929. However, it was his velocity during the play that made him famous. Algebra Based Text Citation: George Gamow and John M. Cleveland, Physics: Foundations and Frontiers , (Prentice-Hall, Inc., Englewood Cliffs, N.J., 1960). Permission granted by the estates of George Gamow and John M. Cleveland. We are now in a position to make use of vectors to deal with more complicated problems in which the forces involved are at an angle to the direction of motion.Figure 4-7 shows a box being dragged along the floor by a rope that makes an angle of 30ø with the floor. Let us say that the box weighs 500 lb and that its coefficient of friction with the floor is 0.25. How hard will the man have to pull? Since the pull of gravity, W, is vertical, and the reaction of the floor against the box can be considered in terms of its vertical and horizontal components, R and Ffr (friction), and the motion of the box is horizontal, it would seem a good idea to break the oblique pull P into vertical and horizontal components also. This gives us: Pv = P sin 30ø = 0.5P and: Ph = P cos 30ø = 0.866P free body ref: Citation: H. Q Fuller, R. M. Fuller and R. G. Fuller, "Physics Including Human Applications". (Harper and Row, New York, 1978). Permission granted by the authors. The first step in solving such problems is to draw a free-body diagram (see Figure 4.16b) to show clearly all forces acting on each body. The bodies are connected by a rope; if the rope doesn't stretch or break, both bodies will have the same acceleration. Therefore, the net force on each body must equal its mass times the acceleration. Let us solve the problem: For mass A: There is no motion perpendicular to the plane, thus, the magnitude of the normal force N must equal the component of the weight acting vertically: N - MA g cos q = 0 or N = MAg cos q = 10.0 kg x 9.80 m/sec2 x 0.800 = 78.4 N. For mass A to move up the plane, we must have a net positive force acting parallel to the plane: T - (MAg sin q + mN) = MAa summary 2d motion: This is an easy concept to grasp. I enjoyed the example of the football player greatly. It is important to always think of velocity as speed and direction when solving a problem. Another important concept to understand when working with two dimensionas motion is vectors, which is why I included this selection with the football selection. summary free body: Free body diagrams are very usefull. It helps the problem solver to isolate the forces on a given object hence making the problem solving process much easier. To draw a FBD you must define an axis in which to relate your forces, then find all forces on the object and draw them. That is what a FBD is. What else can be said? 2450486 1997 Feb 06 14:46 xyp29p20.ltec.net 204.96.104.30 student: Brad Kratochvil keywords: (Motion) or ( two dimension) or (free body diagrams) # hits: 7389 # docs: 503 2d ref: Citation: Edwin C. Kemble, Physical Science, Its Structure and Development, (The MIT Press, Cambridge, MA, 1966). Permission granted by the MIT Press. The vertical motion, described by the variation in time of the altitude y, is assumed to follow the same rules as for a body thrown vertically up into the air. Once more we identify s in Eq. 6.18 with the altitude (i.e., with y) and the acceleration a with - g. Reserving the symbol v for the magnitude of the resultant vector velocity in two dimensions, let us designate the initial vertical velocity by w0. Equation 6.18 becomes Citation: Dudley Williams and John Spangler, Physics for Science and Engineering (D. Van Nostrand Company, New York, 1981). Permission granted by Dudley Williams and John Spangler. A particle is initially moving at a velocity of 2 m/s, eastward, and 2 s later is moving with a velocity of 2 m/s, northward. What is its average acceleration during this time interval? free body ref: Citation: H. Q Fuller, R. M. Fuller and R. G. Fuller, "Physics Including Human Applications". (Harper and Row, New York, 1978). Permission granted by the authors. Examples 4.3 Citation: H. Q Fuller, R. M. Fuller and R. G. Fuller, "Physics Including Human Applications". (Harper and Row, New York, 1978). Permission granted by the authors. fig 4-4a summary 2d motion: For motion in two dimensions the x and y vectors are independent. When a force acts upon the y vector,the x vector is not affected unless a force acts upon it. When a force is plotted on an x-y axis the horizontal component is equal to the cos of the angle and the verticle component is equal to the sin of the angle. summary free body: I mainly found diagrams of free body diagrams. These diagrams are pictures of all the forces acting upon an object. They are used to make the picture of the object simpler and easier to understand. 2450491 1997 Feb 11 18:48 xyp169p15.ltec.net 207.91.14.73 student: Mitch Riley keywords: free body diagram or 2d motion or motion in two demensions # hits: 283 # docs: 88 2d ref: motion in two demension Conceptual-Level textbook In one dimension, reflected waves simply travel back in the direction from which they came. In two dimensions, waves are reflected from a boundary in a slightly more complex manner. If we compare the direction of motion for incoming and reflected waves, we see a pattern. Rays describe the direction in which incoming and reflected waves move. As shown in Figure 14-13, (See original text) incoming rays and reflected rays make equal angles with a line perpendicular to the boundary. The angle made by the incoming ray and the perpendicular called the angle of incidence, is equal to the angle made by the reflected ray and the perpendicular, called the angle of reflection. This relationship is called the law of reflection: Spears, J., & Zollman, D., "The Fascination of Physics" (The Benjamin/Cummings Publishing Company, Inc., 1985) free body ref: algebra-based textbook Even the simplest illustration of how Newton's second law should be used requires that we understand how to isolate a body whose motion we wish to analyze. Suppose that a smooth wooden block with a mass of 7 kg is going to be pulled by a horizontal force of 8 nt. We have a spring balance calibrated in newtons. It is convenient, when we use the second law, to draw a free-body diagram--that is, a diagram in which we isolate the body, perhaps by drawing a dashed curve round it (our artist has laid a patch of color over it)--and draw vectors representing all the external forces acting on it. In Figure 24.9 the block is drawn with three vectors on it: W, the weight, which is the gravitational pull of the earth on the block; R, the force of reaction of the table on the block; F, the pull exerted by the cord connecting the block and the spring balance. We assume that R exactly balances W, for, if it didn't, there would be a vertical acceleration, and there is none. That leaves only F as the unbalanced force, which is, then, the F that is used in the second law. On the assumption that there is no friction (which may not be a good assumption in some cases) we can predict what the acceleration will be. From the second law, a = F/m, we get Citation: Albert V. Baez, The New College Physics: A Spiral Approach, (W. H. Freeman and Company, San Francisco, CA, (1967). Permission granted by W. H. Freeman and Company and the author. summary 2d motion: Motion in Two Dimensions: Just from enrolling in math courses I had a good idea what 2D space was and I learned what motion was in physics, so putting the two together and combining that knowledge with what I found in the infomall I am able to summarize 2D motion as; Motion that is not restricted to a straight line path, it can turn or circle, it can go in any direction as long as it remains in a set plane. The motion can not extend out of a plane otherwise it would become 3D motion. summary free body: Free Body Diagrams: From reading through the infomall I learned that a free body diagram is a tool used to help you solve for, or understand all the forces that are applied to some object, or objects. here is a quote from the textbook trove defining free body diagram--" a diagram in which we isolate the body, perhaps by drawing a dashed curve round it and draw vectors representing all the external forces acting on it. 2450504 1997 Feb 24 00:57 abeln619a.unl.edu 199.240.52.111 student: Lee jirovsky keywords: motion, dimensions, diagrams # hits: 275 # docs: 66 2d ref: Citation: Spears, J. and D. Zollman. "The Fascination of Physics," (The Benjamin/Cummings Publishing Company, Inc., 1985) C3. The best way to use Newton's laws in analyzing two-dimensional motion is to treat each dimension independently. As an example, consider a bale of hay dropped from an airplane to cattle stranded by bad weather. The airplane travels horizontally at a constant velocity of 20 m/s, east. The bale has a mass of 20 kg. Citation: Edwin C. Kemble, Physical Science, Its Structure and Development, (The MIT Press, Cambridge, MA, 1966). Permission granted by the MIT Press. So long as we confine our attention to motion parallel to a fixed line, we can discuss the addition and subtraction of vectors by means of ordinary algebra. In one dimension the signed number representing the sum or difference of two vectors is simply the ordinary algebraic sum or difference, as the case may be, of the signed numbers that represent the original vectors. free body ref: Citation: Albert V. Baez, The New College Physics: A Spiral Approach, (W. H. Freeman and Company, San Francisco, CA, (1967). Permission granted by W. H. Freeman and Company and the author. . It is convenient, when we use the second law, to draw a free-body diagram--that is, a diagram in which we isolate the body, perhaps by drawing a dashed curve round it (our artist has laid a patch of color over it)--and draw vectors representing all the external forces acting on it. In Figure 24.9 the block is drawn with three vectors on it: W, the weight, which is the gravitational pull of the earth on the block; R, the force of reaction of the table on the block; F, the pull exerted by the cord connecting the block and the spring balance. We assume that R exactly balances W, for, if it didn't, there would be a vertical acceleration, and there is none. That leaves only F as the unbalanced force, which is, then, the F that is used in the second law. On the assumption that there is no friction (which may not be a good assumption in some cases) we can predict what the acceleration will be. From the second law, a = F/m, we get summary 2d motion: Motion in two dimensions is simply like evaluating each two one dimensional motions. For every force there can be attributed a perpendicular and parallel component to that force. The relationship between the three can be used to find any particular one. summary free body: A free body diagram is a simple sketch of a system so that the relationships between the interacting components of the system can be easily seen. This helps in keeping track of all the information and can be used to make comparisons and set up equations. 2450504 1997 Feb 24 00:57 abeln619a.unl.edu 199.240.52.111 student: Lee jirovsky keywords: motion, dimensions, diagrams # hits: 275 # docs: 66 2d ref: Citation: Spears, J. and D. Zollman. "The Fascination of Physics," (The Benjamin/Cummings Publishing Company, Inc., 1985) C3. The best way to use Newton's laws in analyzing two-dimensional motion is to treat each dimension independently. As an example, consider a bale of hay dropped from an airplane to cattle stranded by bad weather. The airplane travels horizontally at a constant velocity of 20 m/s, east. The bale has a mass of 20 kg. Citation: Edwin C. Kemble, Physical Science, Its Structure and Development, (The MIT Press, Cambridge, MA, 1966). Permission granted by the MIT Press. So long as we confine our attention to motion parallel to a fixed line, we can discuss the addition and subtraction of vectors by means of ordinary algebra. In one dimension the signed number representing the sum or difference of two vectors is simply the ordinary algebraic sum or difference, as the case may be, of the signed numbers that represent the original vectors. free body ref: Citation: Albert V. Baez, The New College Physics: A Spiral Approach, (W. H. Freeman and Company, San Francisco, CA, (1967). Permission granted by W. H. Freeman and Company and the author. . It is convenient, when we use the second law, to draw a free-body diagram--that is, a diagram in which we isolate the body, perhaps by drawing a dashed curve round it (our artist has laid a patch of color over it)--and draw vectors representing all the external forces acting on it. In Figure 24.9 the block is drawn with three vectors on it: W, the weight, which is the gravitational pull of the earth on the block; R, the force of reaction of the table on the block; F, the pull exerted by the cord connecting the block and the spring balance. We assume that R exactly balances W, for, if it didn't, there would be a vertical acceleration, and there is none. That leaves only F as the unbalanced force, which is, then, the F that is used in the second law. On the assumption that there is no friction (which may not be a good assumption in some cases) we can predict what the acceleration will be. From the second law, a = F/m, we get summary 2d motion: Motion in two dimensions is simply like evaluating each two one dimensional motions. For every force there can be attributed a perpendicular and parallel component to that force. The relationship between the three can be used to find any particular one. summary free body: A free body diagram is a simple sketch of a system so that the relationships between the interacting components of the system can be easily seen. This helps in keeping track of all the information and can be used to make comparisons and set up equations. 2450517 1997 Mar 09 22:52 www-ax0.proxy.aol.com 152.163.233.133 student: Gabe Petersen keywords: Free body diagrams or two dimensional motion # hits: 176 # docs: 79 2d ref: We can, however, give a general treatment of the special case of two-dimensional motion of a rigid body in which all particles in the body move in paths that are parallel to a single plane. The kinematical and dynamical treatment of this important type of motion is not difficult because the moving body has only three degrees of freedom: translation along two axes, which we can take as X and Y, and rotation about a third axis parallel to Z. Citation: Dudley Williams and John Spangler, Physics for Science and Engineering (D. Van Nostrand Company, New York, 1981). Permission granted by Dudley Williams and John Spangler. The best way to use Newton's laws in analyzing two-dimensional motion is to treat each dimension independently. C3. The best way to use Newton's laws in analyzing two-dimensional motion is to treat each dimension independently. As an example, consider a bale of hay dropped from an airplane to cattle stranded by bad weather. The airplane travels horizontally at a constant velocity of 20 m/s, east. The bale has a mass of 20 kg. free body ref: Even the simplest illustration of how Newton's second law should be used requires that we understand how to isolate a body whose motion we wish to analyze. It is convenient, when we use the second law, to draw a free-body diagram--that is, a diagram in which we isolate the body, perhaps by drawing a dashed curve round it (our artist has laid a patch of color over it)--and draw vectors representing all the external forces acting on it. Citation: Albert V. Baez, The New College Physics: A Spiral Approach, (W. H. Freeman and Company, San Francisco, CA, (1967). Permission granted by W. H. Freeman and Company and the author. The first step in solving such problems is to draw a free-body diagram (see Figure 4.16b) to show clearly all forces acting on each body. Citation: H. Q Fuller, R. M. Fuller and R. G. Fuller, "Physics Including Human Applications". (Harper and Row, New York, 1978). Permission granted by the authors. summary 2d motion: Two dimensional motion deals with motion in which a body moves in directions parallel or perpendicular to a single x,y plane. Also this motion holds only certain freedom's, as they say in the first citation. Two dimensional motion deals mainly with vertical, horizontal and rotation motion, in a polar coordinat system. summary free body: Free body diagrams are tools used by physicists to help them visualize the forces acting on a certain object or certain system, so that they can better their calculations. 2450574 1997 May 05 16:13 xyp176p12.navix.net 207.91.14.112 student: Paul Waggener keywords: Compound search "motion in two dimensions" # hits: 43 # docs: 12 2d ref: Citation: Spears, J. and D. Zollman. "The Fascination of Physics," (The Benjamin/Cummings Publishing Company, Inc., 1985) Citation: Arnold B. Arons, A Guide to Introductory Physics Teaching, (John Wiley & Sons, New York, 1990). Permission granted by John Wiley & Sons, Inc. free body ref: Citation: Arnold Arons, "Thinking, reasoning and understanding in introductory physics courses," The Physics Teacher 19, 166-172 (1981). Permission granted by the editor, C. Swartz and the author. summary 2d motion: For two dimensional motion in the xy plane under constant acceleration, these expressons are motion in the y-axis and onr in the x-axis. A good way to see what is going on is to look at Projectile motion. Because it is equuivalent to horizontial motion at constant velosity and verticle motion at constant acceleration. summary free body: The way i look at free body diagrams is a three step process as follows: 1. I imagine the partical to be isolatid or cut free from its surroundings. Hense the name "free-body diagram". Then i draw a sketch of its out line shape. 2. I indicate on a sketch all the forces that act on the particle. These forces can be active forces, which tent to set the particle in motion, such as those caused by attached cables, weight, or magnetic & electrostatic interaction. Also rective forces will occure, such as those caused by by the constraints or supports that tend to prevent motion "friction". 3. I show all the forces that are known and label them and show the proper magnitudes and directions.