Learning Activity on Gravity:
Which Way is Down?

Astronaut Mark Lee

Astronaut Mark Lee participates in an extravehicular activity (EVA). Credit: NASA

DID YOU KNOW?

All physical objects are attracted toward each other by the natural force called gravity, but the effects of gravity that we observe can sometimes be misleading. For example, objects that are revolving around Earth in orbit appear to be weightless and we sometimes use the terms "zero-g" or "zero gravity" to describe this observation. Such descriptions often lead to the false belief that these satellites have escaped Earth's gravity, but this is not true! All objects near Earth, regardless of size, speed, or altitude, experience the downward force of gravity toward the center of the Earth!

Next Generation Science Standards

The following Next Generation Science Standards will be taught through this lesson:

NGSS 5-PS2-1. Support an argument that the gravitational force exerted by Earth on objects is directed down.

Clarification Statement: “Down” is a local description of the direction that points toward the center of the spherical Earth.

EXPERIMENT WITH GRAVITY!

Image of book

You will need: a book and piece of paper of roughly the same size.

  1. If you drop the book and the paper, laying flat side by side, from around 12 inches above a table, which do you think will reach the table first? Write down your prediction on the paper, then try the experiment.
  2. What happened? Was your prediction correct? Write down your results. What will happen if you try the experiment again, but this time with the book stacked on top of the paper? Write down your prediction and test it out.
  3. Were the results different this time? Write them down, as well.
  4. Finally, what do you think will happen if you stack the paper on top of the book, and drop them a third time? Write down your prediction and give it a try!
  5. Were you correct, this time? What do you think happened?
  6. What other forces might have been at work during these experiments? Would the results be different if you dropped the items from a higher point?

MORE TO EXPLORE:

Check out these videos for a closer look at gravity near space!

Image of Felix Baumgartner preparing for a high altitude skydive.

Felix Baumgartner prepares for a high altitude skydive! Credit: DailyMail

Picture of the International Space Station as seen from above

The International Space Station as seen from above. Credit: NASA

Imagined view of CYGNSS satellite mission in orbit

The CYGNSS satellite mission. Credit: SWRI