Friction Lab

Friction Page 1

Lab: Friction

William Morris

Leo Hayes High School

Friction Page 2

Purpose: To investigate the coefficient of friction for a given surface and the effects that factors such as weight, surface area and changes to the surface have on the coefficient of friction.

Hypothesis: The smaller the amount of normal force (weight), the less friction created and the least surface area and the greaser the surface the less friction is created. With the increase in normal force corresponding with the increase in friction should balance out “mu”.

Materials: Spring scale, string, 4 textbooks, Pledge

Procedure: 1. Using a spring scale and some string we hooked through the pages of the
We pulled the first text book across the table then estimated the amount of force we needed to apply to the scale attached to the text book to move it at a constant speed and then recorded our guess. 3. Using the string and spring scale we pulled the text book across the table at a constant speed keeping the string parallel to the surface of the table and then recorded the data. 4. From this measured force below, we determined the frictional force that had acted upon the book as we pulled it across the table. 5. Then we pulled the book across the table once more at a different constant speed to ensure accurate friction readings. 6. From the weights of the text book we found earlier we determined the normal force acting on the text book as we pulled it across the table and then recorded it below. 7. We added the second text book, (B), to the first one and pulled them across the table again recording their force of friction. 8. We then repeated this procedure twice more adding a text book each time as recorded below. 9. We then pulled text book, A, on its spine across the table at a constant speed recording the force from the
One being the scales not being accurate and there is no way to fix this except to purchase new scales each time. Another could be the angle we are pulling the book from. There is no way for us to be exactly sure if this force is exactly parallel with the table. When finding our normal force we do not take into consideration the weight of the string and this cannot be fixed as our scales are not this precise. It is unknown if our hand was completely steady while finding our normal force. This could result in our normal force being inaccurate. There is no way to fix this as we are not robots. The same is true for finding the force of friction as we are not sure we are pulling the book(s) at the same constant