TESTING WHETHER ADDING MASS TO A SLINKY WILL CAUSE IT TO TRAVEL FASTER DOWN STAIRS THE FASTER Cameron Abernethy Cary academy ABSTRACT The purpose of the experiment was to see if adding mass to a slinky affected how fast it traveled down the stairs. From the background research, it was hypothesized that adding mass to the slinky would make it travel down the stairs slower. This was hypothesized because adding mass to each side of a slinky would cause more force to be needed to pull the slinky over. To perform the experiment the following steps were performed. First, the materials needed for the experiment were collected. Next, the books were stacked on top of one another to create stairs. After that, the slinky was placed at the top of the books and pushed over the front of the course. Right when this happened the stopwatch was started. Then when the slinky made it to the bottom of the course the stopwatch was stopped. The experiment was then repeated three times for the medium and the large slinky. The results of the experiment was that when mass was added to the slinky, the slinky took longer to travel down the stairs. On average, the slinky with mass added to it took an extra 0.095 seconds to travel down the course. INTRODUCTION The Purpose of the experiment was to find out if a slinky would roll down the stairs faster when there is mass added to both ends of the slinky. When observations were being made, it was found that when one end of a slinky fell down the stairs the other end of the slinky was pulled with it. Then since there is enough force, when the slinky contracts the other back end of the slinky is hurled down the stairs. This is then repeated continually until the slinky reaches the bottom of the stairs. In addition, it was observed that the
slinky is an extension spring. This was concluded because there are three main different types of springs. An extension spring is a spring that when pulled apart, then tries to contract and keep it s shape. When the slinky traveled through the course the same thing was observed. The same thing was observed with the slinky. When the front end of the slinky was dropped down the stairs, the slinky was extended and the back end of the slinky tries to compress with the front end. Also, it was observed that there were 2 main sizes of slinky (medium large). The medium slinky could stretch 46.1 m, and had a mass of 213.65 g. The large slinky could stretch 6.5 m, and had a mass of 287.95 g. It was also found that slinky cannot go down stairs that are wider that 28 cm. The objective of the research was to learn about the physics underlying a spring/slinky. In researching, it was found that a naval engineer trying to invent suspension for one of the navy s ships accidentally invented the slinky. Also, it was found that when a spring is at rest the attracting and repelling forces are always equal or balanced. When a spring is squeezed together, the spring is building up a repelling force that when the spring is let go that force is let out and all of the stored energy is released. In addition, research was conducted in Hooke s law of elasticity. Hooke s law states that a solids displacement has an equal amount of displacement of atoms, molecules, and ions. In addition, it was found that a force that is deforms an object is applied to an object by pushing, pulling or bending the object. When a spring is holding something on one end and is not moving the gravity is equal to KS. There are three main types of springs. The three main types of springs are called compression tension and torsion springs. A compression spring gets shorter as wait is added onto them. When this happens this type of spring pushes back against the load to try to return to its original shape. An extension spring is attached to one object at each end and is pull apart but the spring tries to pull them together again. A torsion spring is a spring that when items on each end of the spring are being pushed together the spring is pushing them apart as well. It was hypothesized that the more mass added to the front of the slinky the slower it will travel down the stairs. This was hypothesizes because the way a slinky travels down the stairs is that
one end of a slinky travels down the stairs the other end is pulled with is. However, since there will be wait added to it the back of the slinky that is being pulled this will cause the back of the slinky to slow down. MATERIALS & METHOD MATERALS Slinky's (large and average sizes) Something that the slinky can travel down (books or stairs) Silly Putty Stopwatch Something to cut the silly putty Excel, one note, or Microsoft word. If none of these programs are available, a pencil and paper. METHOD The control of the experiment was the regular slinky with no mass added to it. The dependent variable was the amount of time it takes for the slinky to travel down the stairs, and the independent variable was the mass of the slinky. Find stairs that the slinky is able to travel down (less than 28 cm wide). Next, if there are no stairs that the slinky can travel down create a custom set of stairs out of books. After that, gather materials that are listed above. Then, place the largest slinky at the highest point of the course. Next, push the slinky over the first stair. As the slinky is pushed start the stop watch. Then, wait for it to travel to the end of the stairs or books. Record how long it took the slinky to travel down the course. Once it reaches the course stop the stopwatch. Record the results. Then, Rap silly putty to the bottom and top of the slinky. Let the slinky sit out overnight so that the silly putty will not be as sticky. After letting the slinky sit, pick up the slinky and observe if
the silly putty is still sticking. If the silly putty is still sticking, let it sit overnight again. Then pick up the silly putty and place it at the top of the track. Then make sure to gather the time recording materials. Push the slinky over at the top of the stairs. When the slinky is pushed start the timer. When the slinky reaches the bottom of the course, stop the stopwatch and record the time that it took to reach the ground. Then, repeat the previous steps with the medium slinky. Place the data in a table and create a graph. Share the results. The purpose of the second experiment was to see what width of the stairs the slink would travel down the fastest. For this experiment it was hypothesized that the less width the faster it would travel. This was hypothesized because the shorter width meant less space for the slinky to cover. To perform the experiment the following steps were taken. First, the materials needed for the experiment were gathered. Next books were placed on top of one another to create stairs. After that, a width of 15cm was measured in between the books. After this, the slinky that traveled down the stairs the most consistently was placed at the top of the books. Next, the slinky was pushed over the first stair and as this happened, the timer was started. When the slinky go to the bottom of the books, the timer was stopped. This was repeated three times and then the same steps were done for the widths 21.5 cm, 31 cm, 12 cm, and 24 cm. Then record and share the results. The purpose of the third experiment was to test if the height of the drop affected how quickly the slinky traveled down the stairs. It was hypothesized the higher the drop in the books the faster the slinky would travel. To perform the experiment the following steps were performed. First, the materials needed were gathered. Then stairs were made from books. Next, the height of the drop was measured. Make sure that the height of the drop is 23cm. Next, the slinky that is the most consistent at traveling down the stairs was selected and placed at the top of the books. Next, the slinky was pushed over the first book and at this moment, the timer was started. When the slinky go to the bottom of the books, the timer was stopped. Then the experiment was repeated three times. Next record
and share the results. Do the following steps but with drops of 13 cm, 28 cm, and 9cm. Share the results. The purpose of the fourth experiment was to see which type of slinky was most consistent at traveling down the stairs. It was hypothesized that the large slinky would travel down the stairs the most consistently. To complete the experiment the following steps were completed. First, the materials needed for the experiment were gathered. Next books were placed on top of one another to create a course for the slinky to travel down. Then the largest slinky was placed at the top step of the books. Next, the slinky was pushed over the first set of stairs. The times out of ten that the slinky was able to travel down the stairs was then recorded. This was done three times. Then the same experiment was performed except for with the medium sized slinky. Then experiment was performed a second time for each of the two Slinkys. RESULTS & DISCUSSION In the first experiment the time that the slinky took to travel down the stairs was recorded with and without the added mass. To create mass silly putty wrapped around the top and bottom of the slinky. The slinky was left out overnight to make sure that the silly putty would not stick to the table and mess up the experiment. Then the silly putty was inspected to see if it was still sticking to the table. The slinky was then run down the course of books with and without the silly putty. It was found that with both sizes of slinky the slinky without the silly putty was about.2 of a second faster traveling down the stairs. During the experiment it was observed that when mass was added to the medium sized slinky the frequency for how many timed it was able to travel down the stairs went down. In addition, it was observed that when mass was added to the larger slinky the consistency was kept the same.
Time taken to travel the course (s) 2.9 2.85 2.8 2.75 2.7 Trial 1 Trial 2 Average 2.65 without silly putty With or without silly putty with silly putty Figure 1: Results for testing how adding mass to a slinky affected its performance. In the second experiment, the time taken to travel the course was recorded. The width of the books was what was changed throughout the experiment. To create the experiment the books were placed at different widths away from one another. When the width needed to be larger, the books overlapped less and when it needed to be smaller, the books overlapped more. It was found that there was no relationship. Based on the data the trails with a width of 21.5cm was the fastest with an average time of 2.74 seconds. The trails for the smallest width had an average time of 2.77 seconds and trials for a course with a width of 24 cm had an average time 2.91 seconds. It was also found that the slinky could not travel down stairs with a width of more than 29cm, and could not travel down a course with a width less than 12cm.In the second experiment it was observed that when the books had very little width the large slinky kept on skipping over steps. Also, it was observed that when the width was too large both Slinkys were not able to generate enough speed to make it to the next drop.
Time taken to travel down the stairs 3.5 3 2.5 2 1.5 1 0.5 0 15 cm 21.5 cm 31 cm 12 cm 24 cm Width of the books Figure 2: Results for testing whether the width of the books affected how fast it traveled down the stairs. In the third experiment, the time taken to travel down the course was recorded. What was changed in the experiment was that the drop in height of the books/stairs. To change the height of the drop different amounts of books were stacked on one another to create change. When the height needed to be larger, the amount of books in between each drop was increased. When the drop needed to be smaller, the amount of books in each drop was less. The slinky was run down the course with different cm drops. It was found that the greater the drop the faster the slinky traveled down the stairs. The greatest drop had an average time of 0.66 seconds faster than the smallest drop. The time taken for the largest drop or a drop of 28cm was 1.99 seconds. The time taken for the smallest drop of 9cm was 2.65 seconds. While experimenting, it was observed that, the slinky was able to go down the larger drops more easily and consistently.
Time taken to travel down the stairs (s) 3 2.5 2 1.5 1 0.5 0 0 5 10 15 20 25 30 Drop of the books (cm) Figure 3: Results for testing whether the width of the books affected how fast the slinky traveled down the stairs. In the fourth experiment, tests were created to see which size of slinky would travel down the course the most consistently. What was changed in the experiment was the size of the slinky. A large and a medium sized slinky were tested. It was found that the large slinky was able to travel down the stairs an average of 8.33 times out of 10, and the medium slinky was only able to complete the course an average 5.33 times out of 10. It was found that the larger the slinky more consistent it is able to travel down the stairs. While experimenting it was observed that when the smaller slinky was able to make it down the course it was much closer to hitting to stairs than the larger slinky. In addition, it was also observed that the smaller slinky seemed to travel faster down the stairs than the larger slinky.
Times out of ten the slinky was able to travel down the course 9 8 7 6 5 4 3 2 1 0 Large Size of slinky Medium Figure 4: Results for testing to see which slinky could travel down the course the most consistently. CONCLUSIONS In the first experiment it was hypothesized that the more mass added onto to slinky the more mass added to the slinky the slower it would move down the stairs. From the data, the hypothesis was proved that when mass was an added to the slinky it traveled slower down the course. The results of the experiment were probably due to the added mass that slowed the slinky down. The mass slowed the slinky down because when the back of the slinky tried to flip over the front end of the slinky the extra mass made it harder for this to happen. A major discovery was that there is no real relation for what width the slinky travels down the stairs fastest. Some improvements for the experiment are that a time that is more accurate can be used. Future experiments could be different types of slinky could be tested (plastic, steel, tin etc.), or seeing if the different surfaces the Slinky's traveled down make a difference in how quickly it travels down the stairs. In addition, a future experiment could be testing if the temperature of the slinky affected the performance. It could also be tested to see if how old a slinky is affects the
consistency that it is able to travel down the stairs. Also an experiment could be done to see if the surface that the slinky traveled down affected the performance of the slinky. REFERENCES Anonymous. "Why does a slinky fall down the stairs." Portage. Portage Inc., 2013. Web. January 30th, 2013. David Macaulay. "The way things work." 1 ed. Boston, Houghton Mifflin: 1988. Print. "Hooke's law." Encyclopædia Britannica. Encyclopædia Britannica Online School Edition. Encyclopædia Britannica, Inc., 2013. Web. 22 Jan. 2013. "spring." Britannica Elementary Encyclopedia. Encyclopædia Britannica Online School Edition. Encyclopædia Britannica, Inc., 2013. Web. 22 Jan. 2013. Wolfson, Don. Toys: Some great stories behind some great inventions. 1st edition. New York: H. Holt, 2000. Print.