Lab Goal: What factors affect the friction between two objects?

Procedure:

Part 1- Testing Surface Type
1. First, take a box and tie a string on the end of it. Attach a spring scale on the end.
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2. Place it on the first surface. (Plain Surface)
3. Drag the box at a constant speed, by the spring scale and record the reading.
4. Repeat step 3 for two more trials.
5. Repeat steps 2-4 for the other surface types. (squishy red rubber [below], wet surface, and little beads)
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Part 2- Testing Surface Area

1. First, take a rectangular box and tie a piece of string to one side of it. Attach a spring scale on the end.
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2. Drag the box across its largest face at a constant speed on a plain surface and record the reading.

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3. Repeat step 2 for two more trials.
4. Tie the string on another side so that a different sized face of the box is face down on the table.
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5. Repeat step 2 and 3 with the new face.
6. Place the box on its last different face and repeat step 2 and 3
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Part 3- Testing the Mass
1. First weigh the box.
2. Attach string and a spring scale to the box.
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3. Drag the box along a plain surface at a constant speed and repeat for two trials.
4. Add 1573 g to the box and weigh it.
5. Repeat step 3 with the added weight.
6. Add 2573 g to the box and weigh it.
7. Repeat step 3 with the added weight.

Part 4- Testing the Angle
1. First take a box and tie a string to the end of it. Attach a spring scale on the end.
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2. Drag it along a horizontal surface at a constant speed and record the reading. This will be the control.
3. Take a ramp and place on brick underneath it at one end creating a ramp.
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4. Measure the angle furthest away from the brick and record.
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5. Drag the box upward along the ramp at a constant speed and record the reading. Repeat for two more trials.
6. Add another brick underneath the ramp.
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7. Repeat steps 4 and 5.
8. Add another brick (now total 3) underneath the ramp.
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9. Repeat steps 4 and 5.

Data/Calculations:

Part 1- Testing Surface Type


Trial 1
Trial 2
Trial 3
Average
Plain Surface
1.5 N
1.5 N
1.5 N
1.5 N
Small Beads
.6 N
.5 N
.6 N
.57 N
Red Squishy Rubber
3 N
3 N
3.1 N
3.07 N
Wet Surface
1 N
1 N
.9N
1.97 N

Part 2- Testing the Surface Area


Trial 1
Trial 2
Trial 3
Average
Largest Face
.5 N
.6 N
.6 N
.57N
Second Largest Face
1.4 N
1.3 N
1.4 N
1.37 N
Smallest Face
2 N
2.2 N
2 N
2.1 N

Part 3- Testing the Mass

Mass of box= 73 grams

Trial 1
Trial 2
Trial 3
Average
Force with no added weight
.1 N
.2 N
.1 N
.13 N
Force with 1573g
5 N
4.7 N
4.7 N
4.8 N
Force with 2573g
6.5 N
7 N
7.5 N
7 N


Part 4- Testing the Angle

Height of Ramp
Length of Ramp
Angle
Force Trial 1
Force Trial 2
Force Trial 3
Force Average
One Brick
8.7 cm
165 cm
3.02 degrees
1.7 N
2 N
1.5 N
1.73N
Two Bricks
14.5 cm
165 cm
5.02 degrees
2 N
2.1 N
2 N
2.03 N
Three Bricks
20 cm
165 cm
6.91 degrees
2.5 N
2.3 N
2.4 N
2.4 N

Conclusion:

Based on the previous experiments, surface type, surface area, mass, and the angle measure affect the friction between two objects. The experimenters tested a plain surface, a low friction surface, a high friction surface, and a slippery surface. All surfaces demonstrated different amounts of friction with a constant mass being pulled along them. The surface that had the most friction was the red, squishy rubber at 3.07 N and the surface that had the least friction was the surface with the small beads at .57 N. These results proved that as one objects travels along different surfaces will differ according to the type of surface. Therefore, the more traction it has on a surface the more resistance it has when its dragged so the force would be greater. Also, the experimenters tested to see how the friction differed for a large surface area compared to smaller surface areas with a constant mass. They realized that the smaller the surface area the greater amount of force was need to pull the object. The experimenters found that the largest surface required the least amount of force to pull it at .57 N. The smallest surface tested required the most force to pull it at 2.1 N. For example, if one were to pull a dresser across their room it would take less force if they laid it on a side with the most surface area, rather than a side that has the least surface area. In addition, the mass played a factor in the force of the friction. The more that was added the more force of friction it took to pull the box. According to the experimenter's data, the box with 2573 grams of weight took an average of 7 N to be pulled, while the box with no added weight only took an average of .13 N on the same surface. Since there was more weight pushing down on the box it took more force to pull it. For instance, pulling a shopping cart that is full with items takes more force than an empty shopping cart. Finally, the angle at which you pull an object affected the force of friction, as well. The greater the angle is the more force it takes to pull it up the ramp. When the experimenters stacked three bricks the angle was at 6.91 degrees and the average force of friction needed to pull it up the ramp was 2.4 N. When only brick was stacked at 3.02 degrees the average force of friction needed to pull it up the ramp was only 1.73 N. So, if one were to pull up a sled up a slightly raised incline the force it would require would be less than if they were to pull that same sled up a much steeper incline. After doing these various trials, the experimenters found that there are many factors that contribute to the amount of friction between two objects.