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Effect of Friction on Objects in Motion

Abstract

The funny thing about friction is that you couldn't get anywhere without it, yet it still acts to slow you down as you're getting there. Here is an easy project to measure the effects of friction.

Summary

Areas of Science
Difficulty
 
Time Required
Short (2-5 days)
Prerequisites
None
Material Availability
Readily available
Cost
Very Low (under $20)
Safety
No issues
Credits

Andrew Olson, Ph.D., Science Buddies

Sources

This project is based on:

Objective

The goal of this project is to investigate how far equally-weighted objects with different surface textures will slide when propelled across surfaces with different textures.

Introduction

Friction is a force between objects that opposes the relative motion of the objects. In this project, you will be studying kinetic friction (also called sliding friction). When two objects are moving relative to one another, kinetic friction converts some of the kinetic energy of that motion into heat. You can feel the heat of kinetic friction if you rub your hands together.

The same thing happens when two objects are sliding past one another-for example, when you push a box across the floor. Part of the energy of your pushing moves the box, and part of the energy is lost to kinetic friction. How much energy is lost? What factors do you think will act to increase or decrease kinetic friction?

Think about what happens if you push a box across a smooth, polished surface like a wooden floor. Now, think about what happens if you push the same box across a rough, carpeted surface. Which surface will require you to push harder? As shown in Figure 1 below, you will have to push harder on the rough surface due to higher friction.

Drawing of a box being pushed on different surfaces

Diagram of a person pushing a box on a smooth surface experiencing lower friction forces (left) compared to a box being pushed on a rough surface (right). A smaller force is needed to overcome the friction force on a smooth surface, and a larger force is needed to overcome the larger friction force on a rough surface.


Figure 1. Friction is higher on rough surfaces than it is on smooth surfaces.

Now, think about what happens if, instead of pushing an object continuously, you slide it across a surface by giving it a big initial push. Will the amount of kinetic friction affect how far the object goes? What types of materials will have the highest friction? In this project you will find out by using a rubber band to launch objects across different surfaces.

Terms and Concepts

To do this project, you should do research that enables you to understand the following terms and concepts:

More advanced students should also study:

Questions

Bibliography

  • This webpage has a good introduction to friction:
    Darvill, A., date unknown. GCSE Physics: Energy, Forces & Motion: Friction, Broadoak Community School, Weston-super-Mare, England. Retrieved November 8, 2006.
  • Wikipedia also has an article on friction:
    Wikipedia contributors, 2006. Friction, Wikipedia, The Free Encyclopedia. Retrieved November 8, 2006.
  • More advanced students should also study Newton's three laws of motion, which are introduced in these four lessons from The Physics Classroom:
    Henderson, T., (n.d.). Newton's Laws, The Physics Classroom. Retrieved accessed May 9, 2014.

Materials and Equipment

To do this experiment you will need the following materials and equipment:

Experimental Procedure

  1. Cover the test area with the surface material to be tested. Use tape to hold the edges of the material down, so it does not slide around.
  2. Set up your rubber-band launch station at one end of the test area.
  3. With the object in contact with the test surface, pull back on the rubber band to some measured distance. Use the same amount of stretch for each object. This insures that the launching force will be the same for each test object. Figure 2, below, shows an example test setup using a ruler.
A rubber band stretched between two fingers on a carpet next to a ruler
Figure 2. The test setup. Use a ruler to make sure you pull the object back the same distance each time, and to measure how far the object travels.
  1. Launch the object horizontally, so that it slides over the test surface. If the object does not stay in contact with the test surface, try again. You may need to use less force, or adjust the height of the rubber band above the surface.
  2. Measure and record the distance the object travels. Make a data table in your lab notebook to record all of your results.
  3. Test each object at least 10 times (more is better).
  4. Calculate the average distance each object travels. More advanced students should also calculate the standard deviation.
  5. Make a bar graph showing the average distance traveled (y-axis) vs. surface combination (test surface and object). Arrange the bars in order of increasing average distance traveled.
  6. Which surface combinations produced the most kinetic friction?
  7. Which surface combinations produced the least kinetic friction?
  8. Can you explain your results in terms of the physical properties of the materials you tested?
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Variations

  • What happens if you hold the test surface and the object constant, but change the weight of the object (by attaching progressively more weight on top of the object)? Make a graph of distance traveled vs. object weight under these conditions.
  • Use a spring scale to measure the force needed to drag various objects across different surfaces. Record both the transient force needed to overcome static friction (Figure 3, left), and the maintained force necessary to counteract sliding friction (Figure 3, right). How do these two forces vary with different surfaces? How do these forces vary with the weight (normal force) of the test object? How do these forces vary with the surface area of the test object?
A spring scale is used to pull a wooden block across the floor   A scale pulling on a block measures the force of friction
Figure 3. Using a spring scale to measure static friction (left) and sliding friction (right) of an object.

Careers

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General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

MLA Style

Science Buddies Staff. "Effect of Friction on Objects in Motion." Science Buddies, 8 July 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/ApMech_p012/mechanical-engineering/effect-of-friction-on-objects-in-motion. Accessed 4 Oct. 2022.

APA Style

Science Buddies Staff. (2020, July 8). Effect of Friction on Objects in Motion. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/ApMech_p012/mechanical-engineering/effect-of-friction-on-objects-in-motion


Last edit date: 2020-07-08
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