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Springs and Slinkies

In this activity, students will understand how potential energy is stored and converted by observing a slinky and a spring in action.

Elastic potential energy is energy stored in objects by tension (like a stretched rubber band) or compression (when you squeeze a spring).

When the potential energy is 'released', it is converted to the energy of motion, also known as kinetic energy. This is the energy you see when the rubber band or spring pops back to its original shape. 

Vocabulary:

Compression: Any of the forces applied towards the centre of structural objects. An engineering term used opposite to tension.

Tension: A force tending to stretch or elongate something. A term used opposite to compression.

Objectives

  • Use a model to explain how potential energy transfers to kinetic energy.

Materials

  • Per Class or Group:
    Slinkies
    3 or 4 large commercial springs
    several small spings (optional: they can be collected from used pens)
    small weights in regular increments (5 g, 10 g, 15 g, etc.)

Key Questions

  • What happens to the potential energy stored in the stretched Slinky when we let go of it?
  • If we stretch the Slinky even further, do you think it will spring back faster or slower? Why?
  • What happens to the springs when we attach the weights to them? Which spring stretches the furthest?
  • Which spring stores the most potential energy?
  • Which spring would spring back the fastest if the weight were taken off? Why do you think so?

What To Do

Part 1: Demonstrate, or have students demonstrate, the following with each of the items.

Part 2: Lead your students in a discussion about potential and kinetic energy.

Teacher Tip: Encourage students to ask questions, make predictions, and discover the conclusions themselves.

Slinky:

  • Have 2 volunteers hold either end of one Slinky and stretch the Slinky by slowly backing away from one another. Watch what happens when it’s released.

Spring:

  • Hold up the springs and observe what happens as you hook the small weights (of varying mass) to each.

Extensions

  • Where there any unintended energy conversions? What where they?