11. Do s and/or k depend strongly on the materials of the contacting surfaces? Explain using your experimental data.

12. Do s and/or k depend strongly on the area of the contacting surfaces? Explain using your experimental data.

13. Does the coefficient of kinetic friction depend on speed? Explain, using your experimental data.

14. Does the force of kinetic friction depend on the weight of the block? Explain.

15. Does the coefficient of kinetic friction depend on the weight of the block?

16. Compare your coefficients of kinetic friction determined in Part III to that determined in Part II. Discuss the values. Do you expect them to be the same or different? Which one do you think is more precise (with smaller uncertainty)? Justify your answer using your experimental data.

Part II (A) Peak Static Friction and Kinetic Friction (large wood surface on table surface) Peak static friction Average (N) peak static friction Kinetic friction force (N) . \"(\"393 kinetic friction (C) Peak Static Friction and Kinetic Friction (large cloth surface of wood block on rough surface) Peak static friction Average (N) peak static friction Kinetic friction force (N) Average kinetic friction Data: Block with no additional mass Acceleration Kinetic friction force (m/sZ) (N) \"k Average coefficient of kinetic friction