Today we did an experiment where we looked at the force of gravity. We estimated and then measured how long a student in our class could hold his arm straight out to the side, while holding up a piece of paper, then 1, 2, 3, and 4 books. We talked about why his arm got so sore trying to hold those objects up... even when it was just a piece of paper - it's because gravity is acting against his arm, wanting to pull it AND the object toward the ground. Here's a shot of our test subject fighting against the force of gravity, to keep that ancient dictionary from being pulled to the earth!
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