# Questions tagged [measurements]

The tag has no usage guidance.

831 questions
Filter by
Sorted by
Tagged with
1k views

### 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.
18 views

### 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

176 views

### 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 ...
52 views

### 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 ...
295 views

44 views

### 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 ...