Teacher Notes



Teacher Notes
Publication No. 13877
The BungeeJumping EggStudent Laboratory KitMaterials Included In Kit
Ceiling hooks, 2
Elastic bands with metal barb ends, 15 Plastic bags, 15 Plastic eggs, 15 String, one spool Additional Materials Required
Water, 500 mL*
Balance, 0.1g precision (one per classroom) Beaker, 600mL* Marker, ink* Mass with hook, 100g (can be shared) Meter stick* Paper towels* Scissors* Clothespin clamp or paper clamp to secure string to the ceiling hook† Stepstool or ladder† Tape measure (to measure platform height)† Trough or catch bucket (optional)† *for each lab group †To make jumping platform Prelab Preparation
Safety PrecautionsIf an egg cracks on the floor, clean up the spill immediately to reduce the risk of a slippery surface. Use caution when standing on a ladder, stepstool or chair when releasing the eggs. Only the teacher should climb on the ladder or stepstool to set up the bungee jump and release the eggs. Wear safety glasses. Please follow all laboratory safety guidelines. DisposalAll the materials should be stored for future use. Teacher Tips
Correlation to Next Generation Science Standards (NGSS)^{†}Science & Engineering PracticesPlanning and carrying out investigationsAnalyzing and interpreting data Developing and using models Using mathematics and computational thinking Constructing explanations and designing solutions Engaging in argument from evidence Disciplinary Core IdeasMSPS3.A: Definitions of EnergyHSPS3.A: Definitions of Energy Crosscutting ConceptsCause and effectScale, proportion, and quantity Energy and matter Systems and system models Performance ExpectationsMSESS12: Develop and use a model to describe the role of gravity in the motions within galaxies and the solar system. Sample Data{13877_Data_Table_1}
CalculationsSpring constant of elastic band: k = (100 g) × (980 cm/s^{2})/19.1 = 5130.9 g•cm/s^{2}•cm = 5130.9 g/s^{2} Calculated stretch distance of elastic band: X = [2 x (66.5 g) × (980 cm/s^{2}) x (263.1 cm)/(5130 g•cm/s^{2}•cm)]^{½} = 81.8 cm String length: SL = 263.1 cm – 75.0 cm – 10.0 cm – 81.8 cm = 96.3 cm Recommended Products


Student Pages


Student PagesThe BungeeJumping EggIntroductionBungee jumping would not be as “safe” as it appears without relying on some basic physics principles, such as the law of conservation of energy and Hooke’s law for springs. A safe bungee jump occurs when no one is injured. A safe and exhilarating bungee jump is one in which no one is injured, the free fall lasts as long as possible, and the bungee jumper comes as close to the ground as possible without touching it. In this activity, the law of conservation of energy and Hooke’s law will be used to build a safe and exhilarating model bungee jump of an egg! Concepts
BackgroundThe law of conservation of energy states that energy cannot be created or destroyed, only converted between one form and another. During a bungee jump, the stored, potential energy of the jumper on a tall platform (PE = mgh) is converted into kinetic energy during the fall (KE = ½mv^{2}). This kinetic energy is converted back into potential energy as the bungee cord stretches. At the bottom of the “ride” when the jumper momentarily stops, all the kinetic energy has been converted into spring potential energy—the energy stored in the stretched bungee cord (PE_{spring} = ½kx^{2}). An instant later, the bungeejumper is flung upwards as the bungee cord relaxes, thereby converting the spring potential energy back into kinetic energy. An egg will simulate a human bungeejumper in this experiment. {13877_Background_Figure_1}
The total height of the jump (h) is the height above the ground at which the jump begins (PH) minus the separation distance (d) between the egg and the ground at the bottom of the ride (Equation 1).
{13877_Background_Equation_1}
PH = Platform height above the floor {13877_Background_Equation_2}
F = force produced by a spring {13877_Background_Equation_3}
By hanging a mass with a known value from the end of the elastic band, and measuring the total length of the stretched elastic band, its spring constant can be calculated (Equation 4).
{13877_Background_Equation_4}
Where m_{u} is equal to the mass value, g is the acceleration of gravity constant (980 cm/s^{2}), and x_{u} is the stretch distance of the elastic band as a result of the hanging mass, m_{u}. Remember that the stretch distance of the elastic band is the total stretched length, x_{T}, minus the unstretched length. To determine the total length of the bungee cord needed for a safe and exhilarating bungee jump, the stretched length of the elastic band at the bottom of the ride must be calculated. Since the initial potential energy of the “jumper” will be converted completely into spring potential energy at the bottom when the elastic band is fully stretched, the initial potential energy will equal the final spring potential energy in the elastic band according to Equation 5. {13877_Background_Equation_5}
Rearranging Equation 5 to solve for x:
{13877_Background_Equation_6}
The calculated stretch distance of the elastic band at the bottom of the ride (X) is therefore equal to:
{13877_Background_Equation_7}
m_{e} = mass of the egg and basket Materials
Water
Balance, 0.1g precision Beaker, 600mL Ceiling hook or rod support platform Egg, plastic Elastic band with metal barb ends Marker, ink Mass with hook, 100g Meter stick Paper towels Plastic bag Scissors String, thin, 150 cm Trough or catch bucket (optional) Safety PrecautionsIf an egg cracks on the floor, clean up the spill immediately to reduce the risk of a slippery surface. Wear safety glasses. Please follow all laboratory safety guidelines. Procedure
Student Worksheet PDF 