Does Length Have an Effect on Speed?

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Updated on May 29, 2013

Grade Level: 3rd - 4th; Type: Physics


To see if the length of a rod or string affects how fast or slow an attached object swings. We will also see if if the weight/mass of the object has an affect on speed when the length is kept constant.


  • Cotton kitchen string
  • Dumbells (or other objects) in various weights
  • Scissors
  • Pen and paper

Experimental Procedure

  1. Cut pieces of cotton string in different lengths. For example, three feet, two feet, and one foot...and so on. These are going to be your variables.
  2. Then tie the string to the dumbell (if needed, secure it with tape).
  3. Hold one of your arms up, this is going to simulate the frictionless pivot of the pendulum. Keep this hand steady.
  4. With your other hand take the weight and drop it from one side of your body and watch it swing back and forth until it stops at the equilibrium position (parallel to your steady hand.)
  5. Now try this with the same dumbell weight, but at a different length of string. What have you noticed?
  6. Now repeat the above steps with the same length of string but a different dumbbell weight. What happened?
  7. Record and analyze your findings.

Terms/Concepts: pendulum; motion; resonant device; restoring force; gravity


Sofia PC is currently a college student with a deep interest in science who is aspiring to become a writer. She writes about all sorts of things across all subjects including, but not limited to; science, crafts, and fashion. She hopes to become a good writer so she can share her thoughts and experiences with the world and future generations.

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