# Tag Info

## Hot answers tagged measurements

44

For this answer, I'll be using this terrible excuse of a ruler, where ┃ is the lines indicating each millimeter and the . is just representing the left-most and right-most face of each of those lines 0 1 2 3 4 .┃. .┃. .┃. .┃. .┃. As I understand it, you're asking whether you should measure 1 mm as: 0 1 2 3 4 .┃. .┃...

28

Gear ratio This is a Roller Chain drive system, and as such it's a timed system. The ratio between the two connected pieces depends entirely on the number of teeth on either end. Even if you altered the diameter of the root of each tooth so the chain can sit higher or lower, at the end of 1,000 revolutions the chain will have moved the same amount on ...

28

You should include the thickness of one total line. In an ideal world, one would measure the the centre of each line (marked 'also correct' below). In this case, you're including half of each line. It's not always easy to judge the centre of the line on a rough plastic ruler, so, assuming that the lines are of equal width, it may be easier to measure from ...

18

I suspect that the answer to this is that, ultimately the gear ratio comes from the ratio of diameters of the gears rather than the number of teeth, although in most circumstances practicality dictates that they are proportional. Say you have a 10 tooth cog and a 40 tooth chainwheel. It's fairly simple to imagine that you could remove every other tooth ...

14

You could just hit a pendulum and measure the angle to which it swings. I have found that three liter soda bottles filled with water and hanging from a rope are good for hitting. Knowing the weight of the bottle, a little trig will give the energy, from which you can get the force. Edit: If the transfer of energy from fist to target happens through a short ...

14

It's important to remember that these pipelines don't exist as a single isolated line and will have a number of branches that tie into the main pipeline and split off for gas to be sold to different locations. This touches on a very broad subject of flow assurance and pipeline network modeling. The pipeline will also be broken into smaller sections by ...

13

Technology used in depth finder, in marine application is mostly like is the best to measure the water from the top. To measure water level from the bottom of tank one could use a piezo electric ceramic transducer combined with an Analog Front End (AFE) and a micro-controller to measure water level. The diagram below best explains the configuration. You ...

13

Grads were developed by the French as part of the metric system and have been referred to as the metric degree. In some countries in Europe surveyors use grads instead of degrees. The other use is by French artillery units who have used grads for decades.

12

Probably the easiest practical method to measure the frequency of a spinning top with everyday equipment is to analyze the sound created by the motion and look for the characteristic frequency. This can be done with a spectrum analyzer app that should be available for free for most smartphones. Place the spinning top close to the microphone of the phone and ...

10

I think what you want is a piezoelectric pressure sensor. You might be able to steal one from an old bathroom scale, but the sensors in a scale may only be good up to ~100 lbs of force. These piezoelectric transducers convert applied pressure to a small voltage across the two leads. This pressure can be converted to force by measuring the surface ...

10

I think that an impact force sensor is what you're looking for. I'm not sure how expensive the linked sensors are so you could also use an acceleration sensor and do a little math. The second option is likely to be less accurate but I suspect that it will also be significantly less expensive! I know you said that you didn't want the complete system design ...

9

The basic problem is that you haven't defined what a "good" kick or punch is. Is the purpose make the opponent lose his balance? To inflict the maximum pain? To break bones? To hit a particular part of the body to disable him? Shatter the most wooden boards stacked on top of each other? Something else? Each of these different outcomes will weigh ...

9

There are a few basic issues. The premise of this idea is that the errors of each measurement device will balance out, so with enough devices, the average value will stay roughly accurate. If not, at least you would be able to notice the difference between the two devices and know when to re-calibrate. For some types of measurements, this is roughly true, ...

9

It could be a tola. 1 tola = 3/8 troy ounce (exactly) = 11.66g (approx.), so 10g = 0.857 tolas. If the scale has an accuracy of 0.01g (it's not very clear from the ebay description!) that would be near enough what is displayed in the picture.

8

From my brief involvement in shocks, I think the most likely solution would be to image the exhaust, probably optically, but maybe using interferometry or something depending on what the exhaust is. The most obvious indication that you have supersonic flow is if you can see a shock diamond. I think you could probably also work it out from the length of the ...

8

Gyrotheodolites are an older, but accurate way to find true north. They can be used on the Earth's surface, but these days they tend to be used for surveying underground, in tunneling and mining applications. GPS surveying methods are replacing gyrotheodolite methods for this application on the Earth's surface. Gyrotheodolites are "surveying instruments ...

8

A "44.2 tooth" gear still can only push 44 links of chain per revolution, which pushes a 16 tooth cog around 2.75 times. There's no getting around that. I think that is the question that has everyone's head smoking. So I made a visualization. Here we have small gear with 40px diameter and 4 cogs and a large gear with 80px diameter and 8 cogs, respectively. ...

7

WARNING: Note that some cheap meters are not suitable for use with 230 VAC AC mains. Some meters may have AC voltage ranges able to conceptually measure to well above AC mains voltage BUT have internal componentry not certified, suitable or safe at eg 230 VAC. Use of such meters to measure such voltages is akin to a safer than usual game of "Russian Roulette"...

7

Simple answer is good multimeters have good protection circuts. When the measuring source outside of the meters capabilities of the meter, the meter will give out of range message. There are four main multimeters categories. They are Category I: used where equipment is not directly connected to the mains (CAT I) Category II: used on single phase mains ...

7

I'm going to offer a slightly less helpful answer by poking holes in the answers of others to explain why they aren't ideal, then offering an incomplete, poorly thought through answer of my own. The majority of answers here suffer from one of three stumbling blocks: they require unnecessarily large jigs to be feasible with complexities which make them ...

7

There are several ways. The most direct is to paint half of the top white and the other black, then point something with a light sensor at it. AC amplify the output a little, then determine the frequency. This could be with a deliberate frequency counter, a scope that displays frequency directly, or a microcontroller you program to find the period and ...

7

Gradians are commonly used in land surveying. I only know this because I made the mistake of asking the same question of a Civil Engineer.

7

Depending on the region and structure of building the techniques might vary. Below are few suggestions Termite inspection is another popular method to determine the structure integrity of building. A handheld radar scanner from DeWalt might also do the job as describe here. Depending on the type of pipes a metal detector might be another good option. Non-...

7

You can use any consistent set of units. That includes SI. But if you try to use a pressure in ATM, a sphere radius in feet, a wall thickness in mils, and want the stress in tons per square inch, you will probably get the wrong answer that you deserve!

6

Conductive foam will change it resistance when compressed, so it makes a good, cheap force sensor, as long as you have a system to make many measurements in quick succession and remember the one with the least resistance. Depending on the force you want to measure, you can use several layers above each other, and because you can cut it into any shape, you'...

6

There are two different aspects in your measurement. On the one hand, you are dealing with tolerances. On the other hand, you cover probabilities in measurement systems. Just for a rough calculation: The probability of the real length to be within 9.8mm and 10mm is 95%. The certainty of this measurement depends on the distribution of your probability. For ...

6

To get that sort of accuracy over that scale is not trivial and probably won't be cheap. For smaller size up to a few meters a portable CMM would be an option (here's an example). These have accuracy on the order of 10 $\mu$m and are used for things like high end/F1 car manufacture. However, CMM type instruments wouldn't be useful for anything larger than ...

6

Answering the question: What are possible types of low cost sensors I can use? There are several types of sensors that can provide millimeter level accuracy. "Low cost" is a very relative term, so you'll need to do some shopping around based on your specific budget. Optical sensors- Included here are those of the type you listed, though it's a very ...

6

Yes To answer your specific question, yes, you can use an ultrasonic sensor to measure fluid level. Mahendra's answer describes that. You mentioned that you feel that an ultrasonic sensor is the best solution, but I wanted to add make sure that you were aware of some of the other methods that are used to measure fluid levels. Measuring Techniques This list ...

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