Answer:
closed
Explanation:
A closed system allows energy (usually heat) to be exchanged but not matter.
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Glass loses electrons easily and silk takes them. Because electrons are negatively charged, the glass rod becomes positive and the silk becomes negative.
Answer:
green light have high energy
Explanation:
We have given the wavelength of the red light 
Speed of the light 
The energy of the signal is given by 
The frequency of the green light is given by:

So energy 
So green light have high energy
She did not have a control group, and she did not expose all three samples to wind. Because her hypothesis was a combination of things, she needed to test the different combinations.
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