Questions tagged [measurements]

Measurements, instrumentation, calibration and metrology.

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14
votes
3answers
5k views

Can I use a ultrasound sensor to measure water level?

If I use an ultrasonic sensor will it detect the water level? I was thinking about a product to read water level on water boxes (common in Brazil). I researched about instrumentation for this ...
28
votes
10answers
6k views

How to quantify martial arts strikes?

Subtitled: Ah, strong am I with the Force, but how do I measure it? With all due apologies for paraphrasing Yoda, I am trying to measure a force. Fortunately, it's an easier force to measure than ...
43
votes
9answers
8k views

Is it possible for a bicycle chainwheel to have a fractional number of teeth?

Background In the world of bicycle motocross, also known as BMX racing, gearing is a hotly-debated topic. Since the bikes are all single-speed, gear ratio is a fixed number defined as ...
22
votes
3answers
1k views

How to know whether the flow is supersonic in a nozzle?

For a project I had built a convergent divergent nozzle designed for Mach number = 3. In that project, I could know the flow has gone supersonic by seeing the manometer fixed between the throat and ...
10
votes
2answers
528 views

How is gas flow through (extremely long) pipelines monitored and controlled?

(This is closely linked with measuring the Mach number inside a nozzle but it is not regarding the supersonic flow) Friction and heat transfer have effects on the Mach number of the compressible flow ...
7
votes
5answers
1k views

What was that?! Quantifying the impact of a martial arts strike

Measuring things like a martial artist's strike can be challenging because it is a complex motion and common vernacular will use imprecise or incorrect terms. This question is an attempt to identify ...
10
votes
6answers
12k views

Distance sensors with accuracy of 1 mm?

I am making a device for measurements. I would like to measure the distance within accuracy of 1 mm. Range could be 2 cm to 15 cm . I looked at Proximity Sensors but the readings displayed by these ...
5
votes
1answer
825 views

How do I calculate rolling resistance for tire on pavement?

First condition assuming perfect rolling, no slip, from what I understand is that the rolling resistance coefficient can be calculated as the displacement arm of the normal force the tire "feels", in ...
3
votes
3answers
3k views

Rule of Tens/Ten to 1 Rule in Measurement and Inspection

I'm trying to clarify my understanding about the requirements [read: best practices] for measurement resolution and measurement confidence. The "Rule of 10s" is a commonly tossed around guideline ...
3
votes
3answers
246 views

Mechanism for controlling the clamping force

I am working on upgrading a research project on wind energy. They are trying to measure the performance of wind blade designs in a small wind tunnel (i.e. their models are relatively small). What they ...
0
votes
1answer
42 views

what is the range of the measurable relative elasticity with a commonly used strain gauge

I'm looking for a data that what is the typical application range for a common uni directional strain gauge like used in weight scales? I've read about around 200 ppm in a research gate article, can ...
-1
votes
3answers
210 views

Would it be hard to create a camera that could see the whole electro-magnetic spectrum? [closed]

Usual cameras can capture the visible spectrum, and some others the infra-red spectrum. But the world is so much than that, isn't it? I wonder why cameras that could see a larger electro-magnetic ...