Scale Definition and 759 Threads

Many times when i ask about test theories of SR, i am reminded by forum members, that equipment sensitivity, is equivalent to producing more extreme physical values. For example, you don't necessarily have to go faster in speed, in order to have a better measurement of time dilation, if you have...

Triangles ABC and DEF are similar. Triangle ABC has a perimeter of 16cm. Triangle DEF has side of 6cm, 8cm and 10cm. What is the scale factor of triangle ABC to triangle DEF? A. 1/2 B. 1/3 C. 2/3 D. 3/2 E. 2/1 I concluded the answer is D. Am I correct?

Question: My attempt: Does 4.75 amps for the full scale deflection seem okay? Thanks for any help!

All I know is that when you press the button, the LCD icon displays an alarm icon which indicates the alarm has been programmed to sound at the exact time every 24 hours.

Watching the Australian Open and they use a heat stress rating to protect the players. I've searched for the details of how it is calculated without success. Anyone know the formula that they use? Just curious.

I'm a highschool student taking my first year of physics. Excuse this somewhat simple question.I know F=ma. If I placed some ball on a scale the weight would read mass of ball times gravity. My question is: what if I dropped that ball on the scale from some height, what would the scale read at...

Does dark matter only exist with galaxies?What scale does it exist on - is it in small particles or clumps?If it's in clumps, what size might these be and how might they be distributed?

Ok a mechanics questionA bag contains a mass M of sand which is suspended by a hook from an arm of a double-pan balance, a height h above one of the pans. A hole is cut in the bottom of the bag so that sand falls out at a constant rate of m kg/s until the bag is empty. The mass required on the...

Whats the amount of energy allowed at this scale?How much energy can be present without streching space beyound this limit our time?

Question: A man is standing on a scale with his weight pressing down on the scale. What is the conjugate force to the weight force on the scale? What is the conjugate force to the force with which the earth is 'pulling' on the person?My question is, what is the difference between the two...

What are some other real life methods to measure mass?(Other than putting the object onto a weight or a scale)

Poll Question:Which length scale possesses the richest physics?A wake to imagination! {^,^}Choices: Planck, below 10^-33 cm Subatomic, 10^-33 to 10^-12 cm Atomic/Molecular, 10^-12 to 10^-4 cm Anthropometric, 10^-4 to 10^6 cm Planetary/Stellar, 10^6 to 10^15 cm Galactic, 10^15 to 10^23 cm Cosmic...

Question:The universe is an enormous potential well around its gravitational centre. If you try to apply schrodinger's equation to the universe in the same way as an atom, will you arrive at a very large but finite number of allowed states within the well?(universe)42 is just another number

Hi.I have some questions. Why we do not put a degree on Kelvin scale? And Why we start Farenhiet scale from 32oF and not from any other?Thanks.

Does Heisenburg's uncertainty princlaple only work on a quantum scale and if it does then why can we not predict the future because the uncertainty principle would allow it?

Does Heisenburg's uncertainty princlaple only work on a quantum scale and if it does then why can we not predict the future because the uncertainty principle would allow it?

This is going to sound stupid but remember I've never actually done physics at school so I don't know the basics....Can electricity be created between individual particles or atoms or do you need to actually have a structure on a macroscopic scale to generate it?

Summary:: Strap a weight-measuring bathroom scale to your feet and jump on a trampoline: weight measurements at different points of each jump? What is the longest part of the cycle you are in the free-float frame? I am studying Spacetime Physics 2nd ed. by Taylor and Wheeler at the suggestion...

M F Ice Point 77°M 32°F Steam Point 437°M 212°F 437°M - 77°M = 360°M 212°F - 32°F = 180°F ∴ M = 2F M = 2(68°) M = 136° But this is incorrect. The answer is actually 149°M. Please help.

In cosmology we have a scale factor that depends only on time ##a(t)##. Now how can I solve this thing $$\frac{d}{da}(\dot{a}(t)^{-2}) = ?$$ Is it 0 ? Or something else ?

For A, I had multiplied 65 and 9.8 since that’s the force of gravity. For B, I again multiplied 65 and 2.5 (that’s what the scale says it reads. *I believe you multiply them for c and d, but I’m not positive for it. C- I think you multiply then subtract D- I think you multiply and I’m not sure...

'Imagine that you live in a different universe, which may have a different cosmology to our own. You measure the distances to and redshifts of a large number of Type Ia supernovae, and you use the redshifts to calculate the scale-factor of the universe at the time when the supernova exploded...

If we take a flat universe dominated by radiation, the scale factor is ##a(t)=t^{1/2}## which can be derived from the first Friedmann Equation:$$(\dot a/a)^2 = \frac{8\pi G}{3c^2}\varepsilon(t)-\frac{kc^2}{R_0^2 a(t)^2}$$ But suppose I want to show this using the second Friedmann Equation (Also...

Imagine a Universe where the Hubble parameter is truly a constant, in both space and time. How much smaller would such a Universe be 14 billion years ago compared to today? Using the Hubble parameter in terms of scale factor: ##H(t) = \frac{\dot{a}}{a}## leads to the differential equation...

One of the things I have yet to come across in the explanation for the expansion of the universe is the effect of light... Most all of the matter we observe out there are stars - fusing nuclei and radiating EM energy in incomprehensible quantities... And this has been happening since the dawn...

Hi PF! Fluids in low gravity have a natural oscillation frequency ##\lambda = \sqrt{\sigma / (\rho L^3)}##, where ##\sigma## is surface tension, ##\rho## density, ##L## characteristic length. Then given a particular object, say a sphere, is ##L=D## or ##L=r##? How about a channel; would ##L##...

EDIT: As per @Orodruin 's suggestion(s), I have edited my problems and equations, sorry for the confusion as I typed this out hasty. So from this question, I understand I have to find the net force for the first 10 seconds and deceleration for 20 seconds. The scale shows the force with which...

Summary: How is the universe best viewed considering the great difference between smallest and largets things? I am not sure how to phrase this question so forgive me if it is all wrong. I have noticed that science is doing a lot with small, very small things. They also do a lot with big...

There are 3.35*10^25 molecules in one liter of water. If we are given a penny for every molecule, how high could you stack the pennies given that a stack of 17 pennies equals one inch? Or, to further reduce this large number into something more tangible, how many stacks equal to the distance...

Firstly i worked out the scale factor of the universe R(t)/R(t0) = 1/1+z = 1/1+11.1 = 1/12.1 = 12.1^3 = 1/1772 The distance between the galaxies were 12.1 times less than today and the volume was 1772 times smaller than today. Then I think the average density in the universe at that time is...

My reasoning is that 1)at initial condition, net force of stick on the beaker is equal to the weight of the weight minus the buoyant force applied by the water to the weight, which is the tension force in the string. The recorded weight should be equal to mass of beaker + water + net force of...

According to Sean Carroll's The Cosmological constant(https://arxiv.org/pdf/astro-ph/0004075.pdf) (Eqn.20) cosmological observations imply that the magnitude of the vacuum energy density in natural units is given by $$|\rho^{(obs)}_\Lambda|\le (10^{-12}\ \rm{GeV})^4.$$ Does this imply that the...

Good evening everyone. Can you tell me if it is possible to mathematically derive the Bernoulli principle from a microscopic analysis? In particular, in the hypothesis of an incompressible stationary flow, at a constant altitude, it states that: P + 0.5ρV^2 = cost Well, in textbooks this...

In order to get a very general sense of the scale of order of magnification power of telescopes: If a hobby telescope i have, has a magnification power of X100, what would be the magnification power in terms of X, of the following: 1. Hubble 2. James Webb 3. Gravitational lensing

I wrote the following code in MATLAB: t = [0:0.001:0.1]; noise = randn(1,size(t,2)); a = 15*10^9; b = 15*10^(-3); c = 7*10^8; y = a*exp(-t/b)+c+noise*100000000; fun = @(p,t)p(1)*exp(-t/p(2))+p(3); p0 = [15.5*10^9, 14*10^(-3), 6*10^8]; p = lsqcurvefit(fun, p0, t, y); t_fit = [0:0.0001:0.1]; y_fit...

From the continuity equation ##\frac{\partial \rho}{\partial t}+\rho (\nabla • u)=0## where ##\rho## is the mass density and is homogeneous and ##u## is the velocity of expansion or contraction. For an expanding volume this becomes ##\nabla•u=\frac{\dot v(t)}{v(t)}=\Theta## which gives the rate...

If, as suspected, the Andromeda galaxy "colides" with our own sometime in the far future, would the gravitational forces from passing stars have effect on our solar system? In accelerated models the interaction looks quite violent, but how would it be in our "uncharted backwaters of the...

QS) A model of a bus has a scale of 4cm to 3m. The model is 10cm long. What is the real length of the bus? my workout: 4cm to 3m. 4 cm is length of model and 3m is real length. so we have, mode = 10 cm long so 4 cm to 10 cm: 10/4= 2.5 cm for real length 3 X 2.5= 7.5 m. I am not sure about...

Electronegativity has seen a number of scales throughout its years of existence. Starting from the Pauling scale to the Allen scale, Wikipedia has a long list. Recently, Martin Rahm, Tao Zeng and Roald Hoffmann have defined a new scale for electronegativity. The news has been published in...

Homework Statement A closed funnel is 10 meters above a weighing scale. At t=0 we open the funnel. and 15kg of sand are coming out of it every second. The velocity of the sand when it comes out is 13m/s, directed downwards (towards the scale). At a certain moment the scale displays a value of...

Lately I've been really interested in creating a chatbot that could learn and talk to users. The only problem though that's preventing me from starting is the time it may take for the program to find the data it needs in memory. Most chatbots simply find the closest match to your words and then...

G’day. I am here to clear my doubt about the dB scale, in general, and it’s use in calculating received power in a microwave cavity. Given that I have arrived at received power (Pr in Watts) for a given input power (Pt), I understand that 10*log (Pt/Pr) yields Pr in dB. Now, say, the...

Hi. I've just re-read a high school introduction about SR. It introduces the relativistic mass. I know that this concept isn't used anymore in modern formulations of SR, but observations should be the same in all formulations. They make the following thought experiment: An electric tram and...

Homework Statement Is the least count constant for Vernier scale like 0.1 mm or variables? 2. The attempt at a solution If the main scale readings are 10 mm and the vernier scale readings are 9 mm, the least count is MSD/VSD = 9/10 = 0.9 So the least count is 0.1 mm for every count in the...

hi, I'm designing a 50ftx50ft, 8-cable Cable Driven Parallel Robot and am thinking this is a pivotal decision. the corner posts are 10ft tall and the machine should be able to lift 100lbs at least 5ft off the ground. traveling speed of the end effector is less important than accuracy but I'm not...

Ant-Man can shrink to the subatomic quantum realm where space and time cease to have meaning. Can he reaches inside the Planck scale? I wanted to use the words "below" or "above" the Planck scale. But when describing inside it.. do you use "below" or "above" the Planck scale to describe inside...

This is first post so bear with me. This might be totally a blue sky thought ( ok it almost assuredly is ). But when reading about the frame dragging near black holes I wondered if this effect might also be seen ( at a far lower intensity ) in the motion of galaxies. Not suggesting that...

I currently have a cheap digital scale that will measure, say, from 1 g and beyond to the hundredth place with reasonable accuracy, but for anything less than a gram, it is erratic. For example, when I'm adding 0.15 g of a chemical, sometimes the value will change but often it will not and...

I need to scale my solar system model and it's not working. I'm making an augmented reality app that shows a sample solar system rotating. It works great! (Thanks to this $7 program https://assetstore.unity.com/packages/tools/physics/gravity-and-orbits-solar-system-105300 . The Unity engine...

Am I correct in understanding that locally, ie, with respect to circumscribable phenomena, conservation of energy is valid in the cosmos but that otherwise it is/may not be? Otherwise said, the source of dark energy does/may not obey this principle? Or is this a question that does not fall...