Tagged Questions
0
votes
2answers
43 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
48 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
88 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 ...
0
votes
1answer
45 views
Rotation System Dynamics - Unit conversion issues
I'm having issues with unit conversions when for rotational systems. All of my components (spring, mass, damper) come in Imperial units, so I did all my calculations in Imperial. When I convert to ...
1
vote
2answers
106 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
167 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
169 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
343 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
67 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
131 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
105 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
718 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
80 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
434 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
196 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
689 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
479 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
271 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. ...
