-2
votes
1answer
29 views

Physical Quantities [closed]

What are the physical quantities which most relate to their definition? Could you give some examples? The definition I found is: " it is any property which can be measured". In the case of mass the ...
1
vote
1answer
64 views

Distance and velocity question

I know that speed is the derivative of distance. So integrating speed should give you distance. Let's suppose we have a speed which obeys this function: $$ v(x) = 2^{2^x} $$ So at time 0 the speed ...
3
votes
1answer
67 views

$c^4$ in Einstein field equations

I have read many derivations of Einstein field equations (done one myself), but none of them explain why the constant term should have a $c^4$ in the denominator. the $8{\pi}G$ term can be obtained ...
0
votes
1answer
48 views

Simple units question (School) [closed]

A tank has 2000 litres of capacity (Ct). It fills at 5 l/s. It is filled with 800 l at time 0. a) How many seconds will it need to fill half the tank. So I did this: X = time. ...
-3
votes
1answer
47 views

Convert an angle

Can someone show me a formula in order to convert an angle from [V] to degree or rad? (i use aPotentiometer measuring steering angle) Edit: Well let me exlpain it. I photo of my experiment is shown ...
0
votes
1answer
67 views

The position of a particle at any time $t$ is given by $S = V0/a [1-e^{-at}]$. What are the dimensions of $a$ and $V_0$?

To find the dimensions of and V0, I must know the dimension of S and e. So I want to know it.
0
votes
1answer
263 views

How to determine Young's modulus of a wire by Searle's method?

The question is: A student performs an experiment to determine the Young's modulus of a wire, exactly 2m long, by Searle's method. In a particular reading, the student measures the extension in ...
0
votes
2answers
203 views

Taking force, mass and length as base units, find the dimensional formula of velocity [closed]

My doubt is that how can force be considered as a base quantity. Is that possible? How can I represent the dimension of velocity using it?
0
votes
2answers
47 views

Significant error conversion

So here is my question: Say we have measured something to be 15,67 mm and the significant error is $\pm 0,01$mm. then we convert the measurement to meter to be 0,01567m would the significant error ...
1
vote
1answer
48 views

Unit Conversion [closed]

I need to convert this expression $ 81752 \left( \frac{BTU}{in^2 h ºR} \right )$ to $ \left( \frac{Kg}{s^3 ºC} \right )$ Is my draft correct? $ 81752 \left( \frac{BTU}{in^2 h ºR} \right ) ...
-3
votes
2answers
51 views

Other units of resistance [closed]

Resistance is $\frac{V}{I}$, and we get the unit $\Omega$. Another unit is $\frac{W}{A^2}$. How do you derive that unit?
1
vote
1answer
85 views

What volume of helium at standard ambient pressure and temperature is required to lift one kilogram of mass? [closed]

I used the Ideal Gas Law PV = nRT where P is the pressure of the gas P = 1.033 kgf/cm squared V is the unknown volume of the gas n is the amount of substance of ...
0
votes
1answer
111 views

Why do these equations result an incorrect unit for acceleration?

Hello everyone. Imagine an object moving around a certain point on a circular orbit. Magnitude of the velocity is constant during the motion ($|v|$). The orbit radius is $r$. (I'd better notice ...
2
votes
1answer
301 views

How do the units for angular velocity come out of $\omega = \sqrt{k/m}$?

I'm confused about an exercise of a book. I understand that the units for angular velocity is $\text{rad/s}$; but I don't understand, how can I get it from the relation $\omega=\sqrt{k/m}$. Solving ...
-4
votes
2answers
357 views

Basic Physics Question [closed]

I'm having a difficult time answering this question. I think I'm just converting the units wrong somewhere: You're the CEO of a courier company, and you decide to select an electric car for your ...
0
votes
1answer
622 views

How does (kg/m^3) * (m/s^2) * (m) come out to be units of N/m^2? [closed]

To me it seems to come out to be kg/(m*s^2). Is this somehow equivalent to N/m^2?
2
votes
1answer
126 views

Does a 27 hp engine output the same amount of energy as lifting a 1 ton stone block almost 3 meters per second?

I’m trying to get a sense of how much energy a 27 horsepower engine outputs. 27 hp $=$ 20 133 watts (joules/second). Potential energy can be calculated as $E = mgh$ where $g = ~9.8\ m/s^2$ on earth. ...
-1
votes
2answers
113 views

Help me check units [closed]

I need to check units in this equation, I know, that there's Pa in the numerator, but what about the denominator? $p_1$ - pressure in [Pa] $T_1$, $T_2$ - temperature in [K] $\rho_w$ - density $g$ - ...
0
votes
2answers
91 views

Dividing values with units

I'm reading about the subject of heat in a basic physics book. If I am not mistaken the formula to work out how much energy is required to increase the temperature of water is ...
-1
votes
1answer
271 views

Convert units from cal cm^-1 day^-1. to Wm-2

I am trying to calculate the energy budget of a water body and the last term I'm trying to calculate is the energy advected from the water body ($Q_v$). This equation is given by: $Q_v = V ( (T_1 - ...
1
vote
1answer
702 views

When should angles be expressed in degrees vs. radians?

I am trying to calculate the albedo of a given latitude by following the methods of Brutsaert (1982), I have copied the formula below: 3.6 Shortwave and long-wave radiative fluxes Albedo ...
1
vote
2answers
154 views

How to check units?

I've got: $Q=\frac{Er^2}{k}$ how to check the units? I start with $\left[\frac{\text V}{\text m} \, \text m^2\right]$, tried replacing $[ \text V ]$ with $\left[ \frac{\text J}{\text C} \right]$, but ...
1
vote
2answers
384 views

Showing that position times momentum and energy times time have the same dimensions

I've been asked to show that both the position-momentum uncertainty principle and the energy-time uncertainty principle have the same units. I've never see a question of this type, so am I allowed to ...
0
votes
1answer
413 views

CGS Units to SI Units

This may be a stupid question but I am having trouble getting the same result in CGS units as I would if I used SI units for a unitless calculation. I have to calculate $E_c=\frac{m_e c\, ...
2
votes
6answers
1k views

Confused about unit of kilowatt hours

So I am a little confused on how to deal with the Kilowatt hours unit of power, I have only ever used Kilowatts and I have to design a residential fuel cell used as a backup generator for one day. ...
0
votes
0answers
147 views

I'm having trouble understanding the dimensions of this falling body problem

I'm working with this: A 50 kg mass is shot from a cannon straight up with an initial velocity of 10m/s off a bridge that is 100 meters above the ground. If air resistance is given by 5v ...
0
votes
1answer
204 views

Units in cgs system

How do I find the dimensions of this quantity (in $cgs$)... $$\frac{4\pi me^2}{h^2n_o^{1/3}}$$ where $m$ is the mass of electron $e$ is the magnitude of electronic charge $h$ ...
3
votes
1answer
296 views

Help on unit conversion problem

This is a problem from school. I will show my attempt. The question: "The gas constant for dry air R is 287 $\frac{m^2}{s^2*K}$. Assuming the temperature is 330 K and the pressure is 1050 hPa, what ...
1
vote
1answer
2k views

Can x and y axis have different scales? [closed]

In a graph on reflection, can i give the x axis a scale of 4 cms = 10 degrees , and the y-axis a scale of 2 cms = 10 degrees? Will it affect the readings?
0
votes
1answer
111 views

Is this a correct addition to a pipe friction loss calculation?

I've been using this online calculator to work out the difference in pressure and flow between two ends of a pipe: Pipe Friction Calculation for Fluid Flow in a Pipe So far most of it makes sense, ...
0
votes
1answer
1k views

Question Based On Units And Measurements Involving Lengths [duplicate]

The below is the sixth question of the very first chapter from halliday and resnicks fundamentals of physics text,which i'am not able to comprehend. Harward Bridge,which connects MIT with its ...
3
votes
1answer
541 views

Do the trigonometric functions preserve units?

I saw an exercise where you had to calculate the units of $C_i, i=1,2$ from an equation like this: $v^2=2\cdot C_1x$ and $x=C_1\cdot \cos(C_2\cdot t)$ where $x$ means meters, $t$ means seconds ...
0
votes
2answers
1k 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 ...
0
votes
1answer
612 views

Changing magnetic flux graph?

In regards to a graph of the changing magnetic flux in a generator such as this one: a) The equation of the graph should be $\Phi = BA \cos \theta$. As $\theta=\omega t$ (angular velocity*time), ...
-1
votes
3answers
319 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. ...