Friction Lab Report

Question: How many Newtons does it take to pull an object across different surfaces?

Purpose: To learn something new about friction.

Hypothesis: I don’t think the amount of force needed to pull the object will vary too much between the surface types, but there definitely will be a difference.

Procedures:

Written procedures: First, I obtained all of the needed materials (listed in “Materials list”). Second, I had to screw in the metal hook in the car (be sure that the car is de-wheeled). After that, I attached the string to the hook so that it would be more comfortable to use, and the scale would have a more accurate reading. After that was done, my car was placed on its first testing surface, in this case – foam. When I made sure that the foam was secured in place (with my hand or some tape), and that the car’s entire surface lay on the foam, not partially hanging off to the side, I attached the hook of the spring scale to the string attached to the car. When I was successful in doing so, I zeroed out the scale, ad carefully started dragging the car along the foam. When the car made the slightest movement, I recorded how many Newtons it took to make it move. Then switched the surface, and repeated. When I ran out of surfaces, I went back to the top of the table I was making (to foam), and restarted again. When at the end I had four ready columns each filled with the different surfaces I used, I recorded each row’s averages.

Materials list:

One wheel-less car,

Some foam surface,

Some felt surface,

Some foil surface,

Some tabletop surface,

Some sand paper surface,

One metal hook,

Some string,

One spring scale,

One correctly functioning human.

*Tape (Optional)

Observations/Data:

	1st trial	2nd trial	3rd trial	4th trial	Total Average
Foam	1N	.75 N	1 N	1 N	.9375 N
Felt	1.25 N	.75 N	1 N	1 N	1 N
Sand Pap.	2 N	2.5 N	1.75 N	2.25 N	2.125 N
Table	1 N	.75 N	.5 N	.75 N	.75 N
Foil	.75 N	.5 N	.5 N	.75 N	.625 N

Conclusion and Analysis: It is very clear now, that how much force you need to pull an object across different surfaces varies greatly. On the sand paper, the car was extremely hard to pull, where on foil it slid along like on ice. However, sometimes the scale gets off zero, and that could affect the averages, but in general, I can see that my hypothesis was very wrong. Therefore, I came to a conclusion: The amount of force needed to pull an object varies not only by the weight of the object itself and the force acting upon it, but also by the surface type that the object is forced to move on.

New Questions: Would the amount of force needed to pull an object vary depending on incline? What other forces besides friction and gravity act upon an object when it is being forced to move along a surface? Is weighing an object the same thing as finding out how much force it takes to pull an object straight up when only gravity acts upon it?