Ok, sort of a silly experiment I admit. But here’s what we’re going for – there is an invisible force acting on you and the ball. As you will see in later lessons, things don’t change the way they are moving unless a force acts on them. When you jump, the force that we call gravity pulled you back to Earth. When you throw a ball, something invisible acted on the ball forcing it to slow down, turn around, and come back down. Without that force field, you and your ball would be heading out to space right now!
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Here’s what you need:


  • you
  • the Earth (or any planet that’s convenient)
  • a ball

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Download Student Worksheet & Exercises


Here’s what you do:


1. Jump!
2. Carefully observe whether or not you come back down.
3. Take the ball and throw it up.
4. Again, watch carefully. Does it come down?


Gravity is probably the force field you are most familiar with. If you’ve ever dropped something on your foot you are painfully aware of this field! Even though we have known about this field for a looooong time, it still remains the most mysterious field of the four.


What we do know is that all bodies, from small atoms and molecules to gigantic stars, have a gravitational field. The more massive the body, the larger its gravitational field. As we said earlier, gravity is a very weak force, so a body really has to be quite massive (like moon or planet size) before it has much of a gravitational field. We also know that gravity fields are not choosy. They will attract anything to them.


All types of bodies, from poodles to Pluto, will will attract and be attracted to any other type of body. One of the strangest things about gravity is that it is only an attractive force. Gravity, as far as we can tell, only pulls things towards it. It does not push things away. All the other forces are both attractive (pull things towards them) and repulsive (push things away). (Gravity will be covered more deeply in a later lesson.)


Exercises 


  1. What did you determine about gravity and how it affects the rate of falling?
  2. Did changing the object affect the rate of falling? Why or why not?
  3. Did changing the variable affect the rate of falling?  Why or why not?

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Advanced students: Download your Gravitational Force Lab here.


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4SHOW TEST BEGIN: p8;p9;p11;p38;p92


  • you
  • the Earth (or any planet that’s convenient)
  • a ball

4SHOW TEST END


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Comments

6 Responses to “Detecting the Gravitational Field”

  1. larmag0724 says:

    This was very helpful.

  2. When you drop any item while standing on the Earth. The air around us pushes back against the falling item. (also called air resistance). As you pointed out, since the balloon is filled with air, its weight is much closer to the air around it. Styrofoam is heavier and can therefore overcome air resistance at a higher rate.

  3. Hi Aurora,
    How come if I blow up a balloon and drop it at the same height and time as a styrofoam ball, they don’t land at the same time? Is it because the balloon is filled with air?

  4. Welcome to our science program! And my best recommendation is to try it to see if it’s too much for her to handle. There is quite a bit of calculation, but I take it step-by-step so she can go at her own pace. I would try both, the 8th and the high school level, and see which one she is enjoying most.

    We are going through the website together in my live classes which you can access here:
    https://www.sciencelearningspace2.com/science-with-aurora/

    If you need a little help getting started. If not, then jump in and enjoy the content!

    Here’s the high school physics course:
    https://www.sciencelearningspace2.com/grade-levels/high-school/

    Here’s 8th grade:
    https://www.sciencelearningspace2.com/grade-levels/eighth-grade/

  5. alison_freidlin says:

    Hi, we are going to start this Science program for my 8th grader tomorrow.

    A couple questions: Is there any reading material that goes with this?

    Do you think the advanced material would be appropriate for my child? She LOVES science and really picks up concepts quickly. However, math is her most difficult subject and she is behind in math. So if there is a lot of tough math, it may not be appropriate for her.

  6. michelle_gillespie says:

    Hi there. I purchased the 8th Grade Supercharged Science Lessons Plan from HomeSchool Planet. The very first lesson directs me to this page where I am learning that I do not have access to the content. Can someone please help me understand what I’m missing here? Many thanks. — Michelle Gillespie 443-366-4067