Online Lab 2: Friction (Ref Lab 2.4 Friction: The Interaction Between Surfaces on traditional lab manual) het.colorado.edu en simulation forces-and-motion-basics The purpose of this experiment is to find the coefcient of static friction and the coefcient of kinetic friction for different interfaces. As it pulls an object from rest to a constant velocity, the force vs time can be plotted, as shown in figure below, with both the static friction and the kinetic friction. Check the link here to understand the friction from simulating the moving process. https:wwwxhephysicsaviagcomPhysicsProgramst LaszForceFrictionl Figure 1, demonstration of applied force on an object with friction against time. First part depicts the static friction and at part shows the motion with constant velocity. We can also solve for the unknown forces or masses using the equations learned in class using the lab simulation. Run the simulation and click on the Friction tab on the top of the sim. While on the friction tab - select the following settings, DO NOT MOVE THE FRICTION SLIDER >>> With the settings now currently in place you will complete the following chart by manipulating the simulation. Play with it for a few moments to familiarize yourself with the controls. Use the following equations: Ff = \"N and N = mg mmm_ Applied Force Static Friction Coefficient of Friction ------ --- What has to happen before the Applied Force begins to move the box? What happens once you exceed the frictional forces? Explain what happens to the box once you stop applying force? Now we will manipulate the settings and INCREASE the amount of Friction to anywhere on the slide - it must move. Object(s) Mass Weight Normal Force Applied Force Static Friction Coefficient of Friction Trash Can Man Refrigerator 2x Crates Based on the simulation, explain how you were able to solve for the weight of the present - include variables and equations in your answer. There is error with the simulation, when the box began moving, what should have happened regarding friction? Explain your answer in terms of forces and coefficients. Find unknown mass and unknown friction coefficients 1. Unknown mass: Turn on the pause and applied push force, Fp > friction force, Ff (given). Turn off the pause and time the speed change from vi (can be 0) to vf and calculate a = (vf-vi)/At. From Newton's second law, Fp - Ff = ma, find unknow mass m = (Fp -Ff)/a. Repeat the measurement three time to find the average value of a and calculate the percentage error. 2. Unknown kinetic friction coefficient, uk. Ff = ukmg, find uk = Ff/mg. 3. Unknown static friction coefficient, us. Applied push force gradually from 0 to the unknown mass starting to move. Record the force at that moment, Fmax. Using Fmax = usmg, find us = Fmax/mg. 4. There are many ways to determine the unknow mass and friction coefficients. Feel free to measure them use your own creative ways (e.g., accelerate the unknow object to certain speed and remove Fp, time the process to 0 velocity).Questions 1. A box is pushed along a rough surface, but it does not move. What is the relationship between the applied force and the friction? What kind of friction is this? Draw a free-body diagram. 2. A box is pushed along a rough surface with constant velocity. What is the relationship between the applied force and the friction? What kind of friction is this? Draw a free-body diagram. 3. The same box is now pushed with twice the force. What is the relationship between the applied force and the friction? What kind of friction is this? What happens to the box now? Draw a free-body diagram. 4. Now the person who was pushing the box stopped pushing. What is the relationship between the applied force and the friction? What kind of friction is this? What happens to the box now? Draw a free-body diagram. 5. The graph in Figure 2 (from the lab manual) is representative of the force applied to an object as it is pulled across a horizontal surface. Draw a force diagram for each of the positions labeled in the graph. Describe the motion of the object for the positions labeled in the graph. FDI'EE Time Figure 2. Force vs time graph for an object pulled across a horizontal surface