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0
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2answers
2k views

static friction problem without mass

I am having trouble with a physics problem. The problem is as follows: A car is traveling at 54.0 mi/h on a horizontal highway. A) If the coefficient of static friction between road and tires on a ...
1
vote
0answers
665 views

FPS to MKS usage issues

I'm currently taking a high school physics class and we're doing friction problems now. I've been doing the ones that use MKS perfectly well, but when the problems start to use the FPS system, I'm ...
4
votes
1answer
284 views

Avogadro's number

Could I get an explanation of Avogadro's number and how it relates to determining the mass of a substance? My chemistry textbook only serves to confuse me and the Wikipedia article is aimed towards a ...
1
vote
1answer
590 views

Converting Notes to Milliseconds

Given a note duration (whole, half, quarter, etc.), a tempo (in beats per minute), and a time signature, how long does that note last in milliseconds?
1
vote
1answer
93 views

dynamic viscosity in the minute scale

The dynamic viscosity of air is $1.78\cdot 10^{-5}Pas = 1.78\cdot 10^{-5}\frac{kg}{ms}$. How do I convert this to the minute scale? I see a reason for multiplying the value with 60 (because of the ...
2
votes
2answers
725 views

Fundamental units

Is it right that all units in physics can be defined in terms of only mass, length and time? Why is it so? Is there some principle that explains it or is it just observational fact?
0
votes
1answer
382 views

if a force is 1 newton metre, what is it at 2 meters?

If I have a force, say 24 kg/cm what would that equate to at 2cm? I would like to know the formulae for calculating this. For example. If a motor can hold an object of 24kg at 1cm from its pivot ...
-1
votes
3answers
321 views

Help getting the distance an object has moved

What is a distance an object went through at the speed of 14hm/min for 6 hours? I am having problems with conversions. First, I tried passing 14hm/min to m/s. I did it alright. But now I am unsure. ...
0
votes
2answers
1k views

Why does $E=mc^2$ give results in Joules?

Why does $E=mc^2$ give results in Joules ? Why didn't Einstein need to create a separate unit and how come using two standard units (speed of light in km.s and mass in grams) give another result in ...
5
votes
1answer
9k views

How is formula for converting pressure from mmHg to Pa derived?

Today my younger brother asked me from where does the 1 Pa = 0.00750061683 mmHg formula for mercury barometer come. He needs a way to derive it, or an academic source which can be cited. After ...
1
vote
3answers
958 views

Unit conversion help (school) [closed]

Can someone please help me explaining how to convert units in problems like the one below? I've done many things, but I am very unsure of all my methods. Could you tell me what steps should I take? ...
4
votes
1answer
325 views

Dangerous dose of I-131?

I was searching a lot and could only find dosages for curing cancer and allowed emission, but no Iodine-131 dose that could be connected with increased thyroid cancer risk (like, 10mSv is the ...
4
votes
3answers
506 views

What am I doing wrong when I try to make this unit conversion?

I am trying to reconcile data that I have found in one publication (Allen 1969) with data that I found in another publication (George 2003) that synthesized this data. The data is root respiration ...
7
votes
1answer
354 views

Magnetic susceptibility in 1/eV

In this paper the authors refer to transverse susceptibility $\chi_{ \perp}$ [meV $^{−1}$] I was taught that the magnetic susceptibility is dimensionless. How do I get $\chi$ in the above ...
6
votes
2answers
1k views

Converting between brilliance, intensity, and flux

This one should be a bit of a softball, but I can't find it explicitly stated anywhere on the internet, and my basic unit analysis doesn't seem to work. Suppose you have a beam of synchrotron ...
10
votes
3answers
3k views

Coulomb force in SI and cgs

Coulomb force in SI is $ F = \frac{Q1*Q2}{4\pi\varepsilon R^{2}} $ while in CGS $ F = \frac{Q1*Q2}{R^{2}} $ why is it? I mean doesn't it any make difference in dimension? since $ \varepsilon $ ...