Questions tagged [measurements]

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Different precision for masses of moon and earth online

The Google search page for "mass of moon" shows a value with nine significant digits of precision. The corresponding page for "mass of earth" shows a value with only four significant digits. (The ...
95 views

How would someone determine the speed of sound in water experimentally?

I'm in highschool so I'm looking for a highschool-level lab idea.
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how to understand sensitivity of a system

I am reading a book about measurement. It introduces a concept of sensitivity of the system: the output of the system when the input undergoes a small change. Assuming the system can be described with ...
244 views

Measuring very small temperature differences

Can one use a thermometer with $\pm$5 mK accuracy to measure a temperature difference of 2 mK (the measurement is near 100 mK temperature on a sample on an ADR)? Using the same thermometer, I am ...
43 views

Replacing '< x' by a defined value [closed]

I do have a dataset containing nearly a decade of particulate matter measurements. At the lower precision limit of the measuring instrument, there are values given like ...
2k views

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Have we measured the rate at which Jupiter is shrinking?

On most websites that I looked at, it says Jupiter is shrinking 2cm/year (for example wikipedia and Quora). However neither of these website say whether this rate is measurable (the latter says it is ...
342 views

Does a measurement always require the exchange of energy?

Can you measure something about something without adding or removing energy from it? This comment has got me wondering if there is a way to measure a property or a quantity of something without some ...
151 views

How to read numbers reported in this LIGO paper?

I am not sure how to read the numbers in this excerpt from the abstract of GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence: Are the +/- small numbers ...
743 views

How to measure relative phases of quantum states

If I have a large number of identical systems in identical quantum state $\Psi$ and an observable $A$ whose eigenstates are $\alpha_n$: $$\Psi = \sum_n c_n \alpha_n$$ I can get absolute values ...
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How the data or models given in physics or mathematics problems can be obtained in real life? [closed]

When ever there is physics or mathematics problem. we are already given a mathematical model. Can't we make own models from given diagrams or data collected from the problem? sometimes angle is given ...
91 views

What are the effects of compositional changes in a thermocouple's junction?

We use thermocouples (type B) to measure the temperature of metals (Fe, Ag, Pd, etc) in a furnace under pressure. We weld two thermocouple wires together using an arc welder. This junction then comes ...
4k views

Error Analysis involving random errors

The question goes like this: In an experiment, the time period of an oscillating object in five successive measurements is found to be $0.52$s, $0.56$s, $0.57$s, $0.54$s, $0.59$s. The least count ...
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Does the definition of the metre have to take into account spacetime curvature?

The definition of the metre is: The metre is the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second Does this have to be modified in a ...
95 views

Systematic+Random Uncertainty for velocity measurement

I have a question regarding systematic and random uncertainties. I have to measure the mean value of a velocity measurement in flow field at a point. I've recorded say 1000 samples in time, which I ...