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Can you explain gravity? How come two balls hit the ground at the same time?If you hang a one liter bag of formula from a six foot pole and another one liter bag of formula from a three foot pole. Will the bags empty at the same rate ??

All objects are attracted to each other. This attraction is called gravity. Only large objects like Earth have an attraction strong enough to feel.

Everything falls to the Earth at the same speed, it doesn't matter how big or small it is. A falling object falls faster and faster like a car moving down a road. How come they all fall at the same speed?

Isaac Newton showed us that larger objects have a bigger attraction to Earth than small objects. But, the extra attraction is necessary because it takes more force to pull the larger objects down. The result is an equalling out, with the speed staying the same for all objects!

Gravity gets weaker when you move farther away from Earth. If you hold a ball at three feet and one at 6 feet, they will fall at almost exactly the same speed. But if you were on top of a mountain and you dropped a ball, it would fall at a slower speed because gravity isn't pulling as hard.

Submitted by Danielle (California, USA), Matthew (Ontario, Canada), Adrienne (Michigan, USA), G.S.(New Jersey, USA), K(Chennai, India)
(May 18, 1999)

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA