How do Different Surfaces Affect the Momentum of Marbles?

How Do Different Surfaces Affect the Momentum of Marbles?

            Momentum is a part of our everyday life. Motion can be measured by speed, velocity, and acceleration (Tillery, Enger, & Ross, 2008).  Speed is a measure of how fast something is moving.  Velocity is a measure of the speed and direction of a moving object. Acceleration is a change of velocity per unit of time.  In my experiment, I set up a stack of books six inches high and then connected an additional hardback book as a ramp leaning against the stack. This ramp became the incline which marbles rolled down on the selected surface. Exactly two feet from the bottom of the ramp, a string was laid across the floor surface. The procedure of this experiment was to let go of a marble at the top of the book ramp and record the amount of time (velocity) it took for the marble to roll down the ramp, across the testable surface, and reach the string.

            In order to capture accurate results, two different marbles (one small and one large) were tested on each of the surfaces. Five different surfaces were used: a smooth linoleum flooring, a smooth laminate countertop, a hard-wood floor, a level, compacted carpet, and a shag rug. Each marble was tested five times on each surface to ensure truthful results.

The “mean time” of the five tests were calculated and reported in the results below:

	Small marble	Large marble
Smooth linoleum (flooring)	0.4  seconds	0.3  seconds
Smooth laminate countertop	0.5  seconds	0.4  seconds
Hardwood floor	0.6  seconds	0.5  seconds
Compacted carpet	1.0  seconds	0.9  seconds
Shag rug	Did not reach two feet before stopping	Did not reach two feet before stopping

     The speed on all three smooth surfaces was nearly half the time it took the marble to reach the two foot marker on the carpet. The two rug surfaces caused friction on the marble and thereby slowed down the speed of the marble.  Friction affects the momentum of an object by slowing it down.  The conclusion of this experiment is that the more friction a surface area provides against a marble, the less momentum the marble will have.  Momentum is the time it takes to stop a moving object (Tillery, Enger, & Ross, 2008). The faster an object the more momentum it has.  My experiment also proved that the larger the mass of a marble, the greater its speed. These were the results I expected to get based on my knowledge of momentum and friction.

            The procedure of this experiment went well and provided accurate results. I did have to recruit an assistant (my husband) to help release the marble while I timed it. These jobs were too difficult to perform accurately at the same time.

            Changes that could be made to this experiment in order to get different results would be to alter the plane (angle) of the ramp, use cars or other rolling objects instead of marbles, and test the procedure on various other surfaces. I am still curious to see if the difference in time between the small and large marbles would increase if the distance to the target or string was increased.

            I think my sixth grade special education students would have fun setting up this experiment in my classroom. The materials used are all basic classroom supplies. Students could decide on something about the experiment to change and see how the results would be different. In order to make this more engaging for my class, I would have to relate it to something they would be interested in i.e.: skate boarding.  Perhaps I could have the students compare the various skate board design types. Depending on how fast or slow they liked going down the slide, the students would have to determine the best types of surface materials to use in order to improve the slide mean time results.

            The Guided Inquiry method points students in the right direction and avoids false starts.  My Special Education students find it hard to organize their thoughts and procedures.  By using the Guided Inquiry method I could provide higher level thinking prompts such as

(Capobianco, B., & Tyrie, N., 2009):

            How can we….. ;

            In what ways can we…;

            How can we make a design that will ….;

These problem-finding prompts promote discussion and team work and provide direction.  I prefer the Guided Inquiry to the more generic Open Inquiry method.  The most important things I would want my students to take away from this experiment was 1) how friction affects the momentum of an object by slowing it down and 2) how to work well as a team in pursuit of a common goal.

References

Capobianco, B. M., & Tyrie, N. (2009). Problem solving by design. Science & Children, 47(2),            38–41.             Accession Number: 44572240.

Tillery, B., Enger, E., & Ross. F. (2008). Integrated science (4th ed.). New York, NY:
            McGraw-Hill