Student Guide

Falling Physics

Experimenting with forces and variables of falling objects

How does mass affect how fast an object falls?

This resource was originally published in PhysicsQuest 2020: Force & Motion.


How does mass affect how fast an object falls?

  • 2 equal-sized pieces of paper
  • Chair or table (or both)
  • A ruler or metric tape (optional)
  • Beam balance (optional)
  • A camera to record the experiment (optional)
  • A chronometer or something to measure the time (optional)
  • 2 balls similar in size but different mass 2 aluminum tart pans
Experiment 1
Intro

What would happen if you dropped a hammer and a feather at the same time from the same height? Which one do you think will hit the ground first, the hammer or the feather? What if two bowling balls, one 15 pounds and the other 8 pounds, were dropped off the Leaning Tower of Pisa at the same time. Which ball would hit first? What would happen if you repeat the same experiment on the moon? We need you to work with your classmates to design a couple of experiments to test what happens when an object falls. We want you to design experiments that can help find out if the mass or shape of things affects how objects fall.

After reading the introduction, what is your essential question or objective for this activity?

Before the experiment

  • Do you agree with Aristotle or Galileo? Why?

  • What do you think will happen? Write a hypothesis.

Setting up

  • Place the two tart pans on the floor, bottom up, about a foot apart.

  • Select two equal sized balls.

  • If you have a beam balance, find the mass of the two balls and write those values on your notes.

  • Get your timer and camera ready to record your experiment.

  • Make sure to drop the balls at the same time.

  • How many bangs did you hear on the tart pans each time you dropped the balls.

  • Check your slow motion video. Did the video confirm what you heard?

During the experiment
Collecting data

  • Read through the procedures above, do you think any steps need to be added to make the experiment complete? If so, make suggestions here.

  • Draw a labeled sketch of what your experiment will look like beforehand and confirm with all members of the group.

  • Work with your group to collect data for the experiment. If you are recording, make sure that your classmate starts recording before the experiment starts so you do not miss the important parts. Record your data for each time you repeat the experiment below. Look at the video to confirm your observations and write them below.

  • What was the result of the experiment? Did you get the same result every time? Why do you think that is? Any other observations? Share your results with the other groups in your class.

  • What variables are tested in your experiment? Which variable is the independent variable and which is the dependent variable? Explain your choice.

  • Collect your data. Record your results.

Analyzing data

  • What were your results?

    • Which object hit the ground faster?
    • How many bangs did you hear on the floor?
Conclusion

Revisit the opening questions.

  • Was your hypothesis about which object would hit the ground first the same or different than what you observed in your experiment?

  • Now that you have done the experiment, who do you agree with Aristotle or Galileo?

Experiment 2
Intro

To start off, look at the materials we’ve given you. What kind of things can you do with the stuff you have? With your classmates, design an experiment to test if two objects of the same mass but different shape hit the ground at the same time. Use the scientific method to guide the design of your experiment.

Before the experiment

  • What do you think will happen? Write or draw a hypothesis.

Setting up

  • Take the two pieces of paper and crumple one into a ball.

  • If you have a beam balance, find the mass of each piece of paper. Write those values in your notes and observations section.

  • Measure the height from which you will drop the pieces of papers. Make sure it is the same height. Write the height value on your notes and observations section.

  • Get your timer and camera ready for recording.

  • Drop the pieces of paper at the same time.

During the experiment
Collecting data

  • What variables are tested in your experiment? Which variable is the independent variable and which is the dependent variable? Explain your choice.

  • Work with your group to collect data. Record your data and observations below. Make sure you repeat your experiment multiple times to confirm your results.

Analyzing data

  • What were your results?

  • Did your results support your hypothesis and why or why not?

  • Did you get the same results every time? Why or why not?

  • Compare your results from this experiment with results from Experiment 1. What is similar, what is different?

  • Additional observations.

Conclusion

  • Does mass affect the rate of a falling object? Why or why not?

  • Look back at your “Before the Experiment” answers. How did your ideas change over time? Maybe use these sentence starters: “Before the experiment, I thought….Now I think….” or “Before the experiment, I agreed with….Now I agree with…” or “My hypothesis was _____________ using the _______________________ evidence I collected” or “I know now that object fall _________________ on Earth and ____________________ on the moon because of ___________________”.

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