The distance tag has no wiki summary.
13
votes
4answers
504 views
Why are so many forces explainable using inverse squares when space is three dimensional?
It seems paradoxical that the strength of so many phenomena (Newtonian gravity, Coulomb force) are calculable by the inverse square of distance.
However, since volume is determined by three ...
10
votes
0answers
475 views
Why does the moon look bigger at the horizon? [duplicate]
Possible Duplicate:
Why does the moon sometimes appear giant and a orange red color near the horizon?
Why does the moon look bigger at horizon or skyline than at other times e.g. at ...
6
votes
8answers
482 views
Can you completely explain acceleration to me?
I understand what acceleration is, and I know the formula, and I understand it's a vector.
I just don't understand how the equation works exactly. I'm kind of picky, I know, but bear with me.
...
5
votes
1answer
509 views
Most accurate ways to find the average distance between stars in Milky way galaxy
I've already posted here on quora. But, I'm not totally sure if it's the most reasonable method.
Would anyone care to elaborate on how to find the average distance between stars in a given galaxy ...
5
votes
5answers
227 views
How is distance measured to far away stars and galaxies?
What I need is an accurate description of the methods used to determine the distance to Andromeda. The Parallax method is for nearby objects as I presume. The red shift method applies, but how do you ...
4
votes
2answers
425 views
How could scientists know how far a star or galaxy is from us?
How do astronomers measure how far a star (or galaxy) is away from the earth? How would they know that it has taken 13 million years for light to travel in space before it reaches us?
4
votes
2answers
513 views
How do you measure distance to stars within the galaxy?
I know that for close by stars (<50 LY) we can use the parallax effect. And for distant galaxies we use red-shift (& hubble's constant). So how do we measure how far is a star lets say 50,000 ...
4
votes
3answers
197 views
In relativity, what is the difference between a rod that is perpendicular to direction of motion and a rod parallel to the direction of motion?
In Feynman's Lectures on Physics , chapter 15, page 6 he writes about 2 identical, synchronized light signal clocks. These are clocks that consist of a rod (meter stick) with a mirror at each end, and ...
3
votes
1answer
303 views
How do I find the initial velocity in this problem?
An X-ray tube gives electrons constant acceleration over a distance of $20\text{ cm}$. If their final speed is $2.0\times 10^7\text{ m/s}$, what are the electrons' acceleration?
I know this ...
2
votes
2answers
81 views
Spot of my light on the moon
This is a funny question, but worth answering. The distance between the moon and the Earth is 384,400 km. The speed of light is 299792.458 km/s. It will take 1.3 seconds (Approx.) for my laser beam to ...
2
votes
1answer
91 views
Need help with the position of a particle in a velocity-versus-time graph
I am having trouble with a velocity-versus-time graph. I recently took a Physics test that asked this question: The graph shows the velocity versus time for a particle moving along the $x$ axis. The ...
2
votes
1answer
40 views
instrument that measures the distance from a point in space, through a material like bone, to a live wire carrying very low voltage current?
Is there an instrument that can measure electronically the distance from a point in space through something like bone to a very low voltage wire?
1
vote
1answer
140 views
What is the apparent diameter of the sun as seen from earth?
I know this may not be physically accurate.
For my purposes, basically 3D renders, I am assuming the sun rays are parallel rays from an infinitely far lamp. If the sky is clear, what size would that ...
1
vote
1answer
20 views
Calculate the distance between two points from iPhone Camera
I want to calculate the distance between two point from iPhone camera. Suppose I am standing with my iPhone (with camera on) 10 feet far from the object. So my two objects are 10 feet far from me ...
1
vote
1answer
469 views
Relation between comoving distance and conformal time?
In cosmology, we have two quantities and I want to understand the physical relation between these two :
$\chi = \int_{t_e}^{t_0}c\frac{dt'}{a(t')}$ : the comoving distance with $t_e$ the time at ...
0
votes
1answer
76 views
Is there a finite unit of distance that we cannot divide past?
If distance could be divided into an infinite no of units or points, then it seems to me that motion would be impossible since a meter for instance, having an infinite no of points within it (and the ...
0
votes
1answer
66 views
How do we know that time and distance are not discrete?
I know that it is believed that energy is discrete, in that it travels in quanta. I was wondering if there is any evidence which either proves or disproves something similar with both time and ...
0
votes
1answer
2k views
Finding deceleration and velocity using distance and time
A car is moving down a street with no brakes or gas. The car is slowing due to wind resistance and the effect of friction. The road is flat and straight. The only data I have are timings taken at 100m ...
0
votes
1answer
45 views
Is there any case where one would use, snap, crackle or pop?
As we all know, if you differentiate distance with reference to time, you get speed, and likewise, differentiating speed you get acceleration. However, if you keep differentiating, to the rate of ...
-1
votes
1answer
144 views
Distance and displacement of an object on a straight line [closed]
I had this homework problem, but don't actually know if what I did is right, or that I even read the problem correctly. Can someone please tell me if this is the right interpretation of the problem ...
-1
votes
1answer
194 views
Find the distance of a third charge [closed]
The problem I am having is:
Two positive charges (+8.0 mC and +2.0 mC) are separated by 300 m. A third charge is placed at distance r from the +8.0 mC charge in such a way that the resultant electric ...
-2
votes
0answers
39 views
Whats the theoretical max speed to go around the world? [closed]
I light of the new Scramjet tests I have a question thats been bogging me.
I live in Denmark, about the furthest i can travel is to New Zeeland which is roughly on the opposite side of the earth.
...
