1. Starter # 2 FRICTION LAB From the F vs. t graph for a box on a horizontal surface that weighs 5 Newtons, determine the coefficient of kinetic friction. From the F vs. t graph for a box on a horizontal surface that weighs 5 Newtons, determine the coefficient of kinetic friction.  k = _________

2. Starter FRICTION LAB From the F vs. t graph for a box on a horizontal surface that weighs 10 Newtons, determine the coefficients of static and kinetic friction. From the F vs. t graph for a box on a horizontal surface that weighs 10 Newtons, determine the coefficients of static and kinetic friction.  s = f/N = 4/10 =.400  k = f/N = 3/10 =.300

3. Horizontal Surface N = mg At break point, Pull =  s mg After it starts sliding at a constant speed, Pull =  k mg Therefore, to experimentally find the coefficients,  s = Pulling force at break point/mg  k = Pulling force while sliding/mg Therefore, to experimentally find the coefficients,  s = Pulling force at break point/mg  k = Pulling force while sliding/mg

4. Application – Science Notebook Lab Design a lab to determine the coefficients of friction between wood and cork, Teflon, and felt by recreating the friction vs. time graphs and finding the pulling forces at break point and while sliding. Available Equipment: Force sensor Friction blocks with wool, Teflon, and felt surfaces Masses Logger pro / Data studio

5. Data Table for Science Notebook Felt TrialTotal MassNormal Force Friction Force at Break Point Friction Force while sliding ss kk 1 2 3 Average Cork TrialTotal MassNormal Force Friction Force at Break Point Friction Force while sliding ss kk 1 2 3 Average Plastic TrialTotal MassNormal Force Friction Force at Break Point Friction Force while sliding ss kk 1 2 3 Average

6. Science Notebook REPORT ITEMS Starter Data table Sample Calculations Sketch 1 Graph Question: As the mass of the cart increases, how does the coefficient of friction change? Summary Starter Data table Sample Calculations Sketch 1 Graph Question: As the mass of the cart increases, how does the coefficient of friction change? Summary

7. Connection – Put in science notebook Name some real life applications where friction is desirable, and not desirable. Use complete sentences. Name some real life applications where friction is desirable, and not desirable. Use complete sentences.

8. Science Notebook Exit Write a summary for the friction lab.