Make Monkeys Fly in the Blink of an Eye

Introduction

There are a lot of toys that can be launched into the air using a rubber band or similar elastic material. A "flying, screaming monkey" is such a toy (shown in Figure 1, below), reportedly being able to fly up to 50 feet (ft.) after being launched! What could be "scientific" about flying, screaming monkeys? Well, the series of steps you take to launch the monkey—stretching the rubber band and letting go to send the monkey flying—involves a series of energy conversions (or changes). When you stretch the rubber bands in the monkey's arms, you are storing what is known as potential energy inside of it. Think of it like this. When you say someone has the potential to do something, like the potential to play basketball, you are saying it is possible that person could play basketball. Potential energy is the same thing; the rubber band now has the possibility of using its energy; in this case, to fly. The stretched rubber band will not look like it's energized—it will not be moving, or glowing, or hot—but it has more energy than an un-stretched rubber band does. This extra energy (the potential energy) is due to the change in the rubber band's shape.

Figure 1. This is a toy known as a flying, screaming monkey. Its hands each have a small pocket that you can hook over your fingertips. When you pull back on its body, rubber bands in its arms get stretched, giving the monkey potential energy. When you let go of the monkey, it flies through the air — its potential energy has turned into kinetic energy!

The potential energy is stored in the rubber band until you let go of one end and the monkey starts to fly. At this point, the potential energy has been converted (or changed) into another type of energy, called kinetic energy. Kinetic energy is the energy something has due to its motion. What happens to the rubber band's energy when the monkey has launched and the rubber band is un-stretched again? It is changed into heat, or thermal energy. The rubber band is slightly warmer after the toy has been released, the air that was moved by the monkey as it flew is slightly warmer, and the ground is slightly warmer where the monkey landed. The potential energy of the stretched rubber band has been lost to the environment. But that is no problem for you, because you can always pick it up and launch it again!

Ready to make some monkeys fly? The goal of this science project is to understand how the distance the rubber bands are stretched affects how far the toy flies and show your findings on a graph.

Terms and Concepts

• Elastic
• Energy
• Potential energy
• Kinetic energy
• Motion
• Thermal energy
• Graph
• Right angle
• Parallel
• Mathematical average

Questions

• Based on your research, what is the first law of thermodynamics? (It might be a big word, but it's not as hard to understand as it sounds!)
• What kind of energy depends on the position of an object or the arrangement of its parts?
• How is a stretched rubber band similar to a ball on top of a hill?
• What units are used to measure distance in the metric system?

Bibliography

• Energy Kids. (n.d.). Forms of Energy. U.S. Energy Information Administration. Retrieved November 7, 2014, from http://www.eia.gov/kids/energy.cfm?page=about_forms_of_energy-basics
• Watson, D. (2007). Exploring Energy and Technology: Energy Conversions. Retrieved April 7, 2010, from http://www.ftexploring.com/energy/PE-to-KE.html

Materials and Equipment

• Flying Screaming Monkey; available online at www.amazon.com
  • Note: Any toy that can be launched with a rubber band can be used.
• Steel carpenter's square, 24-in. x 16-in.; available at any hardware store
• Tape measure, cloth or metal, 50-ft.
• Lab notebook
• Adult helpers (2)
• Graph paper

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Experimental Procedure

Performing the Experiment

1. Clear the space in which you will be testing of anything breakable. Be sure there are no other people in the area, aside from you and your two adult helpers. The space should be large and open (such as your school gymnasium) to allow plenty of room for the monkey to "fly," which could be up to 50 ft.
2. Have one adult helper hold the carpenter's square steady, on the ground, as shown in Figure 2.
   1. The carpenter's square will allow you to aim the toy at the same angle each time you launch it.
   2. It will also allow you to measure how far you are stretching the rubber band.

Figure 2. The carpenter's square is placed on the ground. A helper holds the carpenter's square and also reads how far the rubber band is stretched.

3. Have another adult helper ready to measure how far the toy flies, using the tape measure. This helper could also record the data in your lab notebook.
4. Hook the ends of the rubber band (on the monkey's hands) onto your fingers, as shown in Figure 3, below. Note: You should practice launching the toy a few times before you begin recording data.

Figure 3. Hook your fingers into the little pockets on the ends of the monkey's arms.

5. Place your fingers, hooked onto the rubber band, at the top of the carpenter's square, at a right angle.
6. Position the rubber band so that it is parallel to the long end of the carpenter's square, as shown in Figure 4, below, but do not stretch it.

Figure 4. Hold the monkey so that its body is parallel to the long end of the carpenter's square.

7. Record the number from the carpenter's square at which the monkey's head rests in a data table, like Table 1, below, in the Starting Head Position column.
   1. This is the number representing zero stretch.
   2. The line that makes the monkey's mouth is a convenient marker.

Starting Head Position (inches)	Stretched Head Position (inches)	Total Stretch (inches)	Distance Flown (inches)	Average Distance Flown (inches)
		18	Trial 1:
			Trial 2:
			Trial 3:
		15	Trial 1:
			Trial 2:
			Trial 3:
		12	Trial 1:
			Trial 2:
			Trial 3:
		9	Trial 1:
			Trial 2:
			Trial 3:
		6	Trial 1:
			Trial 2:
			Trial 3:
		3	Trial 1:
			Trial 2:
			Trial 3:
Table 1. In the first column, record where the head of the toy is on the carpenter's square. In the second column, record where the head of the toy is after it is stretched. In the third column, list the length the rubber band was stretched ("starting position" minus "stretched position"). The number of inches (in.) the monkey is stretched is up to you: 0, 3, 6, 9, 12, 15, 18 in. is one set possible stretch distances.

8. Stretch the rubber band to its maximum length, as shown in Figure 5, below. Record where the head is now in the Stretched Head Position column, and how far the rubber band is stretched in the Stretch column of the data table.
   1. Note: If the un-stretched toy is 6 in. long and the stretched toy is 24 in. long, the amount of rubber band stretch you should record in the Stretchcolumn is 18 in. (24 − 6).
   2. Try to keep the stretched toy parallel to the carpenter's square.
   3. The maximum in your data table (shown as 18 in., below) will vary depending on your particular toy.

Figure 5. Stretch the monkey, keeping its body parallel to the long end of the carpenter's square, as shown here, and write down how far you stretched it before launching the monkey.

9. Let go of the toy and launch it.
10. Using the tape measure, measure how far the monkey flies. Record the distance flown in your data table.
    1. When measuring, stretch the tape in a straight line between the end of the carpenter's square and the middle of the monkey.
    2. Note: If the monkey slid around or bounced after it landed, try again. If it continues to happen, then either find a less-slick floor on which to try the experiment, or have one of the volunteers estimate the initial landing spot.
11. Stretch the toy again, but stretch it 3 in. less than the previous test.
    1. Feel free to change the amount of stretch to another value if you want.
12. Repeat steps 8–12.
13. Repeat steps 8–12 for various amounts of stretch, such as 18, 15, 12, 9, 6, and 3 in.
14. Perform the entire procedure at least two more times. This will show that your results are repeatable.

Analyzing Your Results

1. Subtract the un-stretched length of the toy from the numbers you recorded for where the head of the toy was in relation to the carpenter square.
   1. This corrects for the length of the un-stretched toy, so that no stretch = 0 in., etc.
2. Calculate the average distance flown for each amount of stretch. To calculate the average, add the measurements from each trial for each stretch amount and divide by 3 (because you performed three trials). Ask an adult if you need help with this step.
3. Graph the data with the length of stretch, in inches, on the x-axis and the average distance the toy flew, in inches, on the y-axis. For help creating a graph online, try a website such as Create a Graph.
4. Evaluate the shape of the graph. Is it linear (a straight line) or another shape?