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What is the difference between the control test method and the control variable method How to choose? Is there a difference between doing it at the same time and not at the same time?
The control experiment has two identical experimental equipments, and the experiment is carried out at the same time, in which there is only one variable
Two experiments using the control variable method are listed
Inclined car experiment, Ohm's law
Principles of Aquarius (first semester of junior high school physics people's Education Press - exercise p24 of sound characteristics)
Eight glass bottles of water from less to more
If you tap them, what's the sound from left to right
If you blow into them, will it still sound the same from left to right?
If you tap it, the bottle and the water in the bottle vibrate together. The less water in the bottle, the higher the vibration frequency and the higher the tone. The bottle on the left has the least water, so from left to right, the tone is from high to low
If you blow air into them, it is the air in the water cup that vibrates. The less the air, the higher the vibration frequency and the higher the tone. The bottle on the left has the least water and the most air. So from left to right, the tone is from low to high
You can do the experiment yourself with a water cup~
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