Experiment: Centrifugal Acceleration - Revision history

Sebastian Kuhlen at 08:04, 20 November 2016

2016-11-20T08:04:10Z

Sebastian Kuhlen at 20:24, 11 October 2016

2016-10-11T20:24:43Z

Sebastian Kuhlen: Created page with "This is a placeholder for an experiment added in the upcoming version of phyphox."

2016-10-07T07:18:57Z

Created page with "This is a placeholder for an experiment added in the upcoming version of phyphox."

New page

This is a placeholder for an experiment added in the upcoming version of phyphox.

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 * I canot measure values above xxx. The limit of the sensors may vary a lot across different devices. Some phones cannot measure acceleration above 30m/s², while others can comfortably reach 80m/s². Similar variations apply to the gyroscope.
 * At some point the plot bends unexpectedly. As the experiment is not exactly in the range for which the sensors are typically calibrated, you might have reached a point at which your sensors react no longer linearly. You can check this by repeating the experiment with a different phone (ideally a different brand).
 [[Category:Built-in experiments]]

← Older revision		Revision as of 20:24, 11 October 2016
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−	This is a ~~placeholder~~ for an experiment ~~added~~ in the ~~upcoming version~~ of phyphox.	+	{{Infobox Experiment
		+	\| Name = Centrifugal acceleration
		+	\| Category = Mechanics
		+	\| Sensors = Acceleration (without g), Gyroscope
		+	}}
		+
		+	The experiment "Centrifugal acceleration" is a very efficient and simple way to demonstrate the relation of centrifugal acceleration ''a'' and angular velocity ''ω''. Both can be measured directly with the accelerometer and the gyroscope, so at a fixed radius r, we can easily measure the quadratic function ''a = r·ω²''.
		+
		+	This can be done with any means of rotating the phone fast and safely. Some suggestions would be a salad spinner or a (small) carrousel. You need to be able to control the angular velocity, so you can measure ''a'' as a function of ''ω'' for wide ranges of ''ω''.
		+
		+	==Requirements==
		+	* A means of rotating your phone "safely" and at arbitrary angular velocities, like a salad spinner or a small carrousel.
		+
		+	* As the phone usually is inaccessible in a moving setup, you may want to use the [http://phyphox.org/remote-control/ remote control] for this experiment. So a second device for the remote interface is usually required as well. Alternatively, you can do a timed experiment and try to vary the angular velocity in the pre-set time.
		+
		+	==Setup==
		+
		+	Make sure that your phone is attached to or placed in your rotating device safely and make sure that the radius is constant. For example, in a salad spinner you should add some soft filling material (like cloth) to protect your phone and fix it at the outer part of the spinner. Rotating your phone at a string is unsuitable as the radius changes with the angular velocity when the angle of the string changes.
		+
		+	You should vary the angular velocity (rotation speed) evenly from zero to a "reasonable" maximum speed. If you are using the remote interface, you can comfortably see gaps in your plot and control the angular velocity to fill them.
		+
		+	A good way to verify the quadratic relation, you can check that the plot of ''a'' over ''ω²'' gives a straight line.
		+
		+	==Analysis==
		+
		+	In this case phyphox does not need to do that much. The data of both sensors is averaged over 0.5 seconds to avoid short acceleration peaks due to a bumpy rotation and to increase the precision. Besides that, phyphox only needs to calculate the absolute of each sensor as sqrt(x²+y²+z²) and plot them.
		+
		+	==Problems and resolutions==
		+
		+	* I canot measure values above xxx. The limit of the sensors may vary a lot across different devices. Some phones cannot measure acceleration above 30m/s², while others can comfortably reach 80m/s². Similar variations apply to the gyroscope.
		+	* At some point the plot bends unexpectedly. As the experiment is not exactly in the range for which the sensors are typically calibrated, you might have reached a point at which your sensors react no longer linearly. You can check this by repeating the experiment with a different phone (ideally a different brand).
		+
		+	[[Category:Built-in experiments]]