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Gravity Discussion
Name: nancy
Status: student
Age: 8
Location: N/A
Country: N/A
Date: 1999
Question:
I am a student and would like to teach a project on
gravity. I am suppose to speak to someone who is an expert in scienct. My
questions are; how would you approach children k-12 with gravity? What is
your experience in learning about gravity? What are your "amazing"
assumptions or knowledge about gravity that would be interesting? What
are the best examples of how gravity can be understood?
I hope you can answer my questions! Can you tell me what is your area in
science?
Replies:
Dear Nancy,
There are many misconceptions about gravity. Some of the "amazing"
assumptions include:
"Sir Isaac Newton discovered gravity." He did not discover gravity, but
rather discovered that it existed everywhere in the universe.
"Gravity gets stronger with altitude." It actually gets weaker (very
slightly) with altitude.
"Gravity can turn off." Gravity has no on/off switch.
"When you throw a ball, there is no gravity when it reaches the top of its
path." Gravity is still there. You do not float out of your seat when a
ball reaches the top of its flight.
"There is no gravity in space." If there were no gravity in space, then
the moon, satellites, etc. would not orbit.
"Rotation causes gravity." Mass determines the amount of gravity.
A good start for understanding gravity is to run experiments on how things
behave in a gravitational field. Get a scale that measures force in
Newtons. Take different masses (1/2 kg, 1 kg, 1 1/2 kg, etc.) and measure
thier forces due to the gravitational field. Does it follow a regular
pattern?
Then take same size marbles, but of different materials, say steel, brass,
aluminum, glass, etc. Drop them and see how long they take to drop from,
say, 1/2 m, 1 m, 1 1/2 m, 2 m, etc. If you find it too difficult to
measure, then roll the balls down ramps of equal steepness, and time them
for a roll of 20 cm, 30 cm, 40 cm, . . . 120 cm. Then try changing the
steepness and see how that effects the time.
I am a physicist. I study the interactions of matter, energy, and fields.
Great question!
---Nathan A. Unterman
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Update: June 2012
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