Now that you have the skills to work with forces in two dimensions, we can explore what happens to weight and the normal force on a tilted surface such as an inclined plane. Up until now, we dealt only with normal force in one dimension, with gravity and normal force acting perpendicular to the surface in opposing directions (gravity downward, and normal force upward). We discussed previously that when an object rests on a horizontal surface, there is a normal force supporting it equal in magnitude to its weight. The coefficient of friction is unitless and is a number usually between 0 and 1.0, but there is no theoretical upper limit to its value. If the floor were lubricated, both coefficients would be much smaller than they would be without lubrication. Would keep it moving at a constant speed. The harder the surfaces are pushed together (such as if another box is placed on the crate), the more force is needed to move them.į k = μ k N = ( 0.30 ) ( 980 N) = 290 N f k = μ k N = ( 0.30 ) ( 980 N) = 290 N So when you push to get an object moving (in this case, a crate), you must raise the object until it can skip along with just the tips of the surface hitting, break off the points, or do both. Magnifying these surfaces shows that they are rough on the microscopic level. If, on the other hand, you oiled the concrete you would find it easier to get the crate started and keep it going.įigure 5.33 shows how friction occurs at the interface between two objects. If you were to add mass to the crate, (for example, by placing a box on top of it) you would need to push even harder to get it started and also to keep it moving. Once in motion, it is easier to keep it in motion than it was to get it started because the kinetic friction force is less than the static friction force. But if you finally push hard enough, the crate seems to slip suddenly and starts to move. This means that the static friction responds to what you do-it increases to be equal to and in the opposite direction of your push. You may push harder and harder on the crate and not move it at all. Imagine, for example, trying to slide a heavy crate across a concrete floor. Look at the table of static and kinetic friction and ask students to guess which other systems would have higher or lower coefficients. Explain the concept of coefficient of friction and what the number would imply in practical terms. Ask students which one they think would be greater for two given surfaces. Start a discussion about the two kinds of friction: static and kinetic. If you do not agree with any of their policies then leave this site now.Review the concept of friction. Click here to go to them to find out more about how they use their cookies. These companies collect cookies when their producs are used on my pages. However, this site uses and or embeds Adobe, Apple, GoDaddy, Google, and YouTube products. (If you are a teacher, please feel free to use these resources in your teaching.) The owner of this website does not collect cookies when the site is visited. Graphs must use SI units unless otherwise instructed.īy Tony Wayne.(The example graph below says "light Intensity" and "distance.") This is done by clicking on the labels in Logger Pro's data table. The labels must be appropriate for the experiment.Double click in statistics box and then press the appearance button to make the font large enough to be seen when made smaller in the report.The graph should include a line of best fit with the line's statistics.If you are analyzing a video or photo using Logger Pro, this auto arrange feature will space it on the screen along with the graph and datatable. Use crtl+R, ( +R on a mac,) to auto-arrange the screen before taking a screenshot to put in your report.When turning in a graph that is made from LoggerPro, it must have a certain "look." This take up more than 2/3's of the graph space. The grid takes up 2/3's of the graph space but the line does not. This graph does not take up at least 2/3's of the graph space. These axes are described with labels and units. The independent variable always goes on the vertical axis. The independendent variable always goes on the horizontal axis. The axes on a graph are always made from a labs dependent and independent variables. Math and science also provide us with structure to organize and better communicate with graphs. To better communicate, English classes teaches us how structure our sentences and works of literature. They can help visually recognize trends and more importantly they can be used to create math models between the cause and effects in science. Graphs are a powerful way to model behaviors. It is meant as a prep for class.Ĭlick for the questions that go with this reading It is not everything there is to know about uniform circular motion. This text is meant to accompany class discussions.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |