Science+Friction


 * Lab Title: Science Friction**


 * Authors: Kevin, Alli, Jonathan**


 * Abstract:** The goal of this lab was to find the coefficient of friction when a=0 and a≠0 on two different surfaces; the regular ramp and a red pad. One method was used to find the acceleration; we used LoggerPro to find the acceleration at different angles until we found the right angle. Using this method, we found the angles to be 15°, for a=0, 22°, for a≠0, 50° for when a≠0 for the red pad, and 47° for when a=0.


 * Introduction:** As a wooden block slides along a ramp, it experiences friction. The force of friction and the normal force, when the acceleration is 0, are balanced with the force of gravity. When the acceleration is not 0, the y-component of gravity is the same as the normal force but the x-component of gravity is greater than the force of friction. The relationship between the friction force and the normal force is known as the coefficient of friction ( µ). In this lab, we had to find how the coefficient of friction changes under different circumstances. There were three parts to this lab: finding the µ at two different accelerations, and the µ on the red padding.


 * Methods**: Since the mass was needed in these equations, that was found first. Using a free-body diagram, F grav  was found to be 1N because the mass was about .102kg. Multiplying that by 9.8 is approximately 1N. Then, using the law of sines, F fric =.375 for the first two trials and .760 for the second two. F norm  was .927 for the first two trials and .682 for the second two. Then using the equation µ =F fric /F norm , µ  was found to be .261 for the first two trials and 1.08 for the second two.


 * Results:**
 * Felt Side when a = 0 m/s/s and angle = 15** °


 * Felt Side when a = 1.3 m/s/s and angle = 22** °


 * Wooden Side when a = .63 m/s/s and angle = 50** ° **(Red Pad)**


 * Wooden Side when a = 0 m/s/s and angle = 47** ° **(Red Pad)**

We were able to find that the µ for the felt side of the block at 15° was about .26 in both parts I and II with a percent difference of about 2.65%. In part III, we tried to find the µ of a sticky red pad using the wooden side.


 * Conclusion:** We chose the harder way and used the inclined plane at a very large angle (50°) instead of using a force probe on a horizontal table. After a few trials, we got a coefficient of friction of about 1.08. In the end, changing the acceleration does not affect the coefficient of friction because the only thing that changes the coefficient of friction is the surface. In addition, the angle does not change the coefficient of friction but the force of friction, which works to balance back out in the end with the normal force.