Sling Energy Into Motion

Scripture: 1 Samuel 17

Learning Objectives:

  • Students will learn how David relied on God and a slingshot to defeat Goliath.
  • Students will record data based on their experiment to learn the relationship between potential and kinetic energy when shooting a rubber band to certain distances.

Guiding Questions:

  • How did David’s slingshot skills provide the force necessary to defeat Goliath?
  • How does the distance that we pull a rubber band create potential energy so that we can shoot a rubber band farther?

Materials: one per pair of students: meter stick, pencil, rubber band, chalk, paper for making a chart (or preprinted chart as seen below)

Procedure: Review the story of David and Goliath focusing on how David was a very talented and experienced slingshot user. Provide students with the history of slingshots by explaining that slingshots were used in battle and could have the same force as a bullet. Slingshots were different than the type of toy ones generally used today because the ammunition was swung around and around a loop of leather rather than pulled and released. This builds up potential energy so that the rock can go further with more kinetic energy.

Explain that potential energy is when you are ready to use the energy, but are waiting. Example: squatting before jumping up. Kinetic energy is energy in motion. Example: actually jumping into the air. (For students on the more basic level, do not be too concerned with the vocabulary.)

Let each student get with a partner for the activity.
Give each pair of students the following:
1. Meter stick
2. Rubber band
3. Pencil
4. Chalk
5. Chart

Pre-print the chart below or have students copy from a written example. Have students work with their partner to shoot the rubber band and record the different distances that it goes. For each measurement on the meter stick, they should do 3 trials. One partner will be the aimer and one will be the checker.
1. The aimer will hook the rubber band on the corner of the meter stick.
2. The aimer will pull the band to the distance described on the chart.
3. Aim straight ahead while keeping the stick level. The checker should check the person aiming to make sure that he is level and measuring the correct distance.
4. The aimer will release the rubber band.
5. The checker will mark where the rubber band lands. Example: Write 2 cm T1 for the first box.
6. Record the distance in the chart using meters and centimeters or feet (but be consistent with the unit you chose across the chart).

Distance that Rubber Band Travels When Pulled to Different Lengths
Band pulled to 3 cm Band pulled to 6 cm Band pulled to 9 cm Band pulled to 12 cm
Trial 1 Distance traveled
Trial 2 Distance traveled
Trial 3 Distance traveled

Conclusion: The longer the rubber band is pulled the ______________(shorter/farther) the band travels. Therefore the longer the rubber band is pulled, the ___________(more/less) potential energy there is to create more kinetic energy.

Students should fill out the conclusion statements above.

To simplify it for younger students:
Only try the distances for 3 cm, 6cm, and 12 cm. Rather than measuring each distance traveled, simply compare the distance by sight. Discuss that the further the band is pulled, the further it travels.

Additional Questions:

  • Why is it important for a scientist to do multiple trials with each standardized measure?
  • How did David’s experience as a shepherd defending his sheep from predators, prepare him for defeating Goliath?
  • Think about what you have learned about potential and kinetic energy when using rubber bands. How does this relate to David’s slingshot?
  • Why is it important for a scientist to do multiple trials with each standardized measure?

Supplemental Activity: Repeat the activity, but let students experiment with different objects to sling while keeping the distance the same. Does the weight or density of the object effect the distance that it can be shot? Suggested objects: pomp poms, leaves, marshmallows, pin-pong balls, etc.

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