17 9) Try turning the block so it is on a smaller face (side). What is the effect on the Fir? _ 10) Try moving the block at a faster constant velocity. What is the effect on Fr? Analysis: Create a PROPERLY labeled graph for Fir VS. FN (Force normal should be on your x axis) esc 11) Plot both sets of data on this graph (use different colors for 'Table' and 'Concrete') 12) Draw two lines of best fit 13) Calculate the slopes of both lines. Table slope: Concrete slope: 14) What are the units of the siope? 15) What does the slope represent? Discussion Questions: 16) If your block rested on an incline plane at an angle with the horizontal of 30, what is the magnitude of the normal force acting on your block? Draw the Free Body Diagram.Ifyour block is pulled up an incline plane, at an angle of 30 to the horizontal with the coefficient of friction you "Iculated for the table top surface, what is the magnitude of the force of friction? Draw the Free Body Diagram. 18) Do the same calculation you did for 17, but assuming the surface had the same coefficient as the concrete. 19) A driver of a 1500 kg car slams on the brakes on a concrete road. Calculate the force of friction on: a. A dry road (H = 0.70) b. A wet road (M = 0.30) c. Which one has a greater force of friction? Explain why. 20) A box weighing 800.0 N is pushed across the floor with a horizontal force. If the coefficient of static friction is 0.80 and the coefficient of kinetic friction is 0.60, how much force is required to: a. Start the box moving? b. Keep the box moving? 21) A frictional force of 120 N is experienced by a box pushed along a road at a steady speed. If the box has 25.5 kg of mass, what is the coefficient of friction between the box and the road?22) Tie two blocks together with tape. Using the coefficient of friction you calculated on the table, determine the following values: a. The mass of each block b. Measure the total friction of the system c. The normal force acting on the system of blocks d. The force of friction acting on each separate block . The magnitude of acceleration of the blocks when the first block is pulled with 20 N of force f. The magnitude of tension in the tape/string joining the two blocks Conclusion: How do the following factors effect force of friction and why? Factor Effect (or no effect) on the Force of Friction Nature of Materials Normal force Speed Surface areaName: Don't Cause any Friction Purpose: To determine factors affecting the force of friction. Materials: 1 block of wood, several masses, newton scale. Procedure: 1) Attach a hook to your block of wood (using tape). 2) Measure and record the weight of your block using a newton scale. Weight of your block = Force of gravity = prt sc 3) In what situation is the normal force (FN) equal to the Force of Gravity (FB)? 4) Place your block on your table. What is the normal force exerted by the table? FN = 5) Draw a free body diagram showing all the forces 6) Hook up your newton scale and pull gently acting on the block at rest on the table. sideways (parallel to table) at a CONSTANT velocity. Draw a free body diagram of this situation. 7) When you are pulling at a constant velocity, the force you are exerting will equal the amount of frictional force in the opposite direction. Measure the applied force using a newton scale and pulling the block at a constant velocity. . FA = FFF = 8) Measure the weight of the block. Record the normal force acting on the block. Pull sideways with a constant velocity and measure the applied force. Determine the force of friction when the block is being pulled at a constant velocity. Record all data in the chart below for the block. Repeat steps with increasing masses. Complete steps on a table top and on concrete. Weight (FB) FN FFr Table FFr Concrete Block Block + 100g Block + 200g Block + 500g Block + 1000g Block + 2000gWeight (FB) FN FFr Table FFr Concrete Block 2.9 2-9 2.2 Block + 100g 3.9 3.9 2. 0 4. 0 Block + 200g 4.9 4.9 2.3 . 5.2 Block + 500g 7.8 7. 8 3.0 7 . 1 Block + 1000g 12.7 12.7 6. 2 12.0 Block + 2000g 22. 5 22.5 12.0 18.0 21: 80