Coefficient of Friction Activity Purpose: Analysis and Interpretation: To measure the kinetic coefficient of friction for a surface. 1. Draw a free-body diagram of the block with an applied force just before its starts to Materials: move wood block with string spring balance Draw a free-body diagram of the block as it is being pulled across a surface at masses from 0.10 kg to 1.0 kg constant speed. graph paper 3. Explain why the applied force should be applied horizontally and not at an angle. Analysis: Explain why the block should be pulled at a constant speed. Rearranging the friction equation F, = is Fu we have 5. What is the relationship between the applied force and the fictional force? 6 What is the rolationship between weight and the normal force? T. What is the unit for the coofficiant of friction? Do your calculations show this? Thus if we plot a graph of F, V's Fi and calculate the slope of the best-fil-line, the Write-up: slope will equal the coefficient of friction (al. Make sure the ands on your graph dota and observations match the equation. graphs calculations Procedure: answers to Analysis and Interpretation 1. Choose a suitable wooden block The mass is written on the block. 2. Construct a data table like the one below as a part of your write-up. 3. Place the first mass on the block. Calculate the weight of the total mass Extra mass Weighing scale Wooden block Applied mass of wadden blocks : 225force 4. Drag the block and mass across the surface making sure to pull horizontally and at a constant speed. The spring scale reading is the applied foror. 5. Ropeat stops 3 to 4 for the other masses. 6. On a sheet of graph paper draw a graph for the data. 7. Calculate the slope of the line-of-best-fit for the graph. Data Table: 1253 F. (N) FN (N) FA (N) Fr (N) kinetic kinetic 0.80 0.35 1. 62 162 0.80 0. 40 1. 98 1.96 1.00 0.45 2.12 2 12 1.20 0. 50 3.50 350 1.40 0. 55 3.25 3. 25 1.60 O. 60