Inertia Lab

Introduction: Have you ever seen the old “pull the tablecloth out from under the table setting” trick? Did you ever wonder how that works? Today’s Lab is going to examine the science behind the magic. First you will see a demonstration of one example of inertia. Then you will perform the experiment. During both observe carefully and record all your observations accurately.

Purpose:

  1. To describe why the pennies can be made to drop into the collecting jar using terms discussed in class.
  2. To determine the effect of mass on inertia.
  3. To explain why the two strings break when they do.

General Instructions: (Read the entire Lab handout before beginning.)

  1. Watch the “Break the String” demo. Make and record observations.
  2. Collect materials for “Drop the Pennies” from the teacher.
  3. Read the procedures for “Drop the Pennies” completely.
  4. Perform the Lab, record careful observations.
  5. Write Lab report.
  6. Answer analysis Questions.

Materials:

1. 5 pennies2. collecting jars3. index cards

Procedures:

  1. Start your Lab Report. After reading the entire procedure, write a Problem statement that makes sense (can be answered by the experiment). Write a Hypothesis that makes sense, answers the question you posed and is tested by the experiment.
  2. Place the index card on top of the collecting jar on your Lab table. Place 1 penny on the center of the index card over the mouth of the jar. Slowly pull the index card towards you. What happens to the penny?
  3. Stack all 5 pennies on the index card and slowly pull the card towards you again. Do the results change? Was there any difference at all?
  4. Place one penny on the card again. Find a way to remove the card and have the penny drop straight down into the jar. What do you have to do?
  5. Add pennies one at a time and repeat what you did. Does anything change?
  6. Return materials and complete your Lab report. (? Where should you put your observations?)

Analysis Questions:

1. Explain the motion of the penny when you pulled the card slowly, why did it do

what it did? Use terms from the unit discussed in class.

2. Explain why your method to get the penny to drop straight down worked. How

did what you did affect the properties and forces discussed in the question

above?

3. Did the number of pennies make any difference in your method or your results?

Why do you think this is?

4. Using what you have learned, explain what happened in the “Break the String”

demo? What are the similarities between this and the explanation for the

pennies behavior in the Lab? What are the differences?

Extension (Extra Credit)

  1. Write a Lab Report for the “Break the String” demo.
  2. In your experience, is there another situation where inertia plays a major role? Describe the situation. Come up with a question about the situation. Make a hypothesis. Design an experiment to test you hypothesis. Include materials and procedures. (You can stop here, it is not necessary to actually do the experiment.) If you can perform the experiment, collect data, and complete the Lab report.