Scalar quantity which is the magnitude of velocity.

learn more… | top users | synonyms

2
votes
1answer
29 views

Send a signal from earth to a planet billion light years away.. instantly [duplicate]

If light was infinitely fast, we could just send a light signal from earth to the planet. But I was wondering, if we made a perfectly non-elastic rope as long as the distance between earth and the ...
0
votes
1answer
24 views

Drift speed of electrons when the object is grounded

So I know that the drift speed of electrons is usually pretty slow. Let's say I have a charged sphere and I would ground it over a wire. How fast would the electrons leave the sphere? Would that drift ...
1
vote
1answer
56 views

Calculate speed of proton at infinity [on hold]

I have this problem to solve: Two protons are on the x axis at x=-1 and x=0. An alpha particle is placed at x=2, and the proton on the left is released, find its speed at infinity. I know that this ...
1
vote
2answers
210 views

Position dependent speed, how to compute position

I can't solve a problem: $ A= 0.5 (ms)^{-1}$, $ x_0 = 0.5 m $, $v(t)= A \cdot x^2 $, I have to compute the position at $t=3$ ($x_0$ is the initial position). So my guess is that I should be able ...
11
votes
5answers
2k views

Why would a fat skydiver fall first in free fall?

I was having one of those obnoxious conversations with a friend where he was arguing that a fat skydiver would reach the ground faster than a skinny skydiver. To me it seemed as obvious that the world ...
0
votes
4answers
212 views

Calculate average speed with unknown variable accelaration

I am in the middle of a vehicle tracking project where I have to calculate the distance traveled by the vehicle in a given amount of time. Data I am getting: ...
1
vote
1answer
21 views

Spinning theoretical object moving faster than the speed of light [duplicate]

Let's say you have the Earth, or any celestial body, spinning as it is. What if you build a tower from the surface, and extended it out into space. If it was built far enough, could the furthest end ...
2
votes
2answers
101 views

Shouldn't the Uncertainty Principle be intuitively obvious, at least when talking about the position and momentum of an object?

Please forgive me if I'm wrong, as I have no formal physics training (apart from some in high school and personal reading), but there's something about Heisenberg's Uncertainty Principle that strikes ...
3
votes
2answers
287 views

Origin of motion and relative speed of bodies in the universe

Charged particles can hit the earth at relativistic speeds. But it seems that all large bodies have fairly low relative speed. Of course, speed can increase considerably when a body orbits close to a ...
29
votes
3answers
3k views

Speed of sound at temperatures below 0 °C

How can the speed of sound be calculated for temperatures below 0 °C (down to -40 °C)? Does the calculation $v=331\ \frac{m}{s} + 0.6 \frac{m}{s°C} \times T$ still hold (where T's unit is ...
48
votes
14answers
12k views

Why does kinetic energy increase quadratically, not linearly, with speed?

As Wikipedia says: [...] the kinetic energy of a non-rotating object of mass $m$ traveling at a speed $v$ is $mv^2/2$. Why does this not increase linearly with speed? Why does it take so much ...
-3
votes
1answer
59 views

Finding the constant of gravity in a game [closed]

Minecraft is a game of mining where one digs and finds ore (to put it simply). the world is composed of "blocks" 3 dimensional cubes that have different "pictures" on them, that make them appear like ...
38
votes
7answers
3k views

Is it fair to judge this speedskating race by only 3 thousands of a second?

I'm reading this article: Zbigniew Brodka of Poland won the Olympic men's 1,500 meters speed skating title by just 0.003 seconds at the Adler Arena on Saturday. Brodka clocked one minute, ...
1
vote
1answer
41 views

Ultra Deep Field 3D camera speed

I guess most of you saw Ultra Deep Field 3D video. In the end it shows camera moving in 3D perspective through all the galaxies. My question is, how fast is the camera moving in that video? I couldn't ...
2
votes
2answers
119 views

What are the consequences in high-energy of the non-interaction of the Higgs Field?

At high-energies when the Higgs field won't affect (interact with) particles, when the symmetry breaking won't occur, what would be $\rm W\pm$ or $\rm Z^{0}$ bosons speed if they would then have a $0$ ...
-2
votes
1answer
39 views

Displacement inside the moving Object

Suppose say a person is standing over the moving bike and he jumps while bike is moving, bike will move forward & person will land in same point at which he jumped, relative to earth position ...
0
votes
1answer
125 views

Distinguish between instantaneous speed and instantaneous velocity

I encountered a line in my text book of physics that: Average speed over a finite interval of time is greater or equal to the magnitude of the average velocity. But instantaneous speed at an ...
0
votes
3answers
185 views

Relationship between power and max. speed

I'm talking about the maximum speed if let's say I have a car with the power $P = 1000 \text{W}$ and a force of friction of $5 \mbox{N}$ acting in the opposite direction. After some googling I found ...
4
votes
2answers
173 views

Gravitation not instantaneous = non elliptic orbits?

When I studied physics some time ago my teacher explained that if we consider the gravitational atraction not instantaneous, such as the General Relativity says, the planets would be attracted towards ...
4
votes
3answers
199 views

Why does a “speed of sound” exist?

I've recently read that wind cannot be faster than the speed of sound (german source). But why is there a speed of sound? I understand (well, mostly accept to be honest) that the speed of light in ...
-4
votes
1answer
73 views

From where we can view earth moving?

Earth moves with a speed around $100000 \,\,km/h$, which will be amazing, but from where we can see that moving speed? If we far away from earth (outside of earth gravity) then can view its moving? is ...
2
votes
1answer
279 views

How to Calculate temperature, given speed of sound and relative humidity?

I know the solution in reverse direction, but I find it very complex to go the other way around and calculate the temperature when given the speed of sound and relative humidity, any ideas?
0
votes
0answers
57 views

Light bodies at high speeds behave like heavy objects when recorded by a high speed camera

This is potentially a very dumb question, but recently I was looking at some slow motion footage of bullets hitting stuff and I realized something interesting. One of the clips showed two metal ...
0
votes
1answer
40 views

How is the universe is experienced at light speed? [duplicate]

When moving faster, we experience time dilation and space contraction. We often state that a photon does not travel through time, i.e. if it where capable of observation, it would not experience time. ...
-2
votes
1answer
54 views

What distance has the soldier travelled? [closed]

A troop $5$ meters long starts marching. A soldier at the end of the file steps out and starts marching forward at a higher speed. On reaching the head of the column, he immediately turns around ...
2
votes
2answers
176 views

What does it mean to be stationary?

I'm looking for a simple answer. What do we regard a stationary. Do we mean an object that is not moving noticeable from the viewers perspective because then a parked car would be considered ...
3
votes
1answer
1k views

How fast do electrons move through a conductor?

If I apply $1 \text{ V}$ across a $1 \text{ }\Omega$ resistance, I'd get $1 \text{ A}$ flowing. $1 \text{ A}$ is defined as $1 \frac{\text{C}}{\text{s}}$, and $1 \text{ C}$ is equivalent to ...
5
votes
2answers
199 views

Is there a limit to frames per second to be captured?

Today we see ~100,000 fps cameras for hyper slo-mo. Is there a physical limit for frames per second for a camera? Speed of light maybe? How?
1
vote
3answers
3k views

Is the same amount of electricity used for ceiling and table fans on different speeds?

We use ceiling and table fans in home which are can be set to low or high speeds using regulators. I want to ask that does it uses or consumes same amount of electricity at different speeds? Here, ...
7
votes
6answers
67k views

How to calculate average speed [closed]

I recently encountered a puzzle where a person drove 120 miles at 40mph, then drove back the same 120 miles at 60mph. The average of the speeds is (40mph+60mph)/2 = 50mph, so the total trip time ...
-2
votes
1answer
95 views

How Was the Speed of Light Discovered? [closed]

The title pretty much says everything; I just want to know how the speed of light was discovered.
1
vote
3answers
219 views

Is there an upper limit on the radius of a rotating wheel?

Is there an upper limit on the radius of a real wheel which is rotating at an Angular frequency of $\,\omega \,$ along its axis, such that we just require a finite amount of energy to rotate it? ...
-2
votes
1answer
162 views

How to calculate the dependency of speed and weight of a servo? [closed]

Here is a digital servo: Servo By using the information of details of that thing what is the way to calculate the dependency of the speed of the movement of the car if the load upon the servo is N kg ...
2
votes
1answer
103 views

Speeds and frames of reference

When reports state that Voyager is traveling at ~17kmps or that a comet is traveling at 600kmps, what are these numbers relative to? Given that the Earth travels at ~30kmps and orbits the Sun which is ...
0
votes
1answer
60 views

Speed Distribution [closed]

I came across a problem which reads: The speed distribution function of a group of N particles is given by: $dN_v = kv\; dv\; (V>v>0)$ $dN_v = 0 \; (v>V) $ (a) Draw ...
1
vote
1answer
48 views

Does speed of writing data on an optical disk affect the speed of reading data? [closed]

Does speed of writing data on an optical disk ( like DVD ) affect the speed of reading data from that disk ? even a little?
10
votes
2answers
759 views

Is it possible to travel at precisely the speed of sound?

I've been talking to a friend, and he said that it's impossible to travel at exactly the same speed as the speed of sound is. He argued that it's only possible to break through the sound barrier using ...
-2
votes
1answer
374 views

Average speed question [closed]

Find your average speed if you go 15m/s for 1000 m and then 30m/s for 1000 m I understand that average speed is total distance / total time. The distance for this problem would be 2000m travelled. ...
-2
votes
1answer
132 views

Calculation of 12000 Lunar Orbits/Earth Day [closed]

I am really interested in the calculation of the following speed value in meter-per-second unit: Speed of something that is able to travel in one earth day the distance that it would take for the ...
0
votes
1answer
376 views

Gentle slope vs steep slope

Take for example a slide of 3m tall. Would an object (starting from rest) sliding down a gentle slope have a lower speed than a steep slope? (Note: Height of slide is the same,disregard friction.) ...
2
votes
3answers
4k views

Why does an object with higher speed gain more (relativistic) mass? [duplicate]

Today, in my high school physics class, we had an introductory class on electromagnetism. My teacher explained at some point that an object with a very high speed (he said it started to get somewhat ...
1
vote
2answers
191 views

How much more energy would I spend if my bicycle was 2 kilos heavier? [closed]

I have a bicycle weighing 8 kilos. An 10 kilometer ride averaging 20 km/h requires z kWh's of energy. How much more energy would I spend if I added 2 kilos to my ...
1
vote
0answers
73 views

Could Elon Musk's proposed Hyperloop transportation system reach 760 mph? [closed]

Hyperloop is a proposed mode of High speed transportation by Elon Musk. Theoretically it's speed is about 760 mph. Can 760 mph speed be achieved with this project ? Hyperloop - Alpha - ...
-1
votes
4answers
886 views

How does a train, airplane measure its speed?

I always get the doubt about this. I know that a bike measures its speed based on the motion of its front wheel. So what is the case with train? Is it same principle? Then what about an airplane? Is ...
0
votes
1answer
110 views

How much speed is maintained in a 90 degree turn? [closed]

How much speed is maintained in a 90 degree turn? Is there an equation for this? I was recently driving and took a 90 degree turn while coasting at 25 mph and it did not seem like I lost very much ...
7
votes
3answers
2k views

What is the speed of time

When we measure the speed of a moving element we do it with the help of a reference frame. Now if we need to measure the speed of time, is it possible? Is time really has speed? Thanks in advance.
2
votes
1answer
176 views

Steel rod to Mars vs the speed of sound, how is supersonic travel possible?

I remember reading this passage in the "Feynman Lectures", where Dr. Feynman describes an experiment in which a theoretical metal rod of length equal to the distance between Mars and Earth is arranged ...
-2
votes
3answers
117 views

Is it possible to defy time using speed? [closed]

I have always wondered if we were to travel at past the speed of light (even beyond the current capability) would we be able to slow down time around us? I have asked my teacher at school and he has ...
0
votes
3answers
267 views

Velocity is “Distance/Time” in a particular direction OR simply “Displacement/Time”?

Is velocity: Distance/Time in a particular direction, or simply Displacement/Time? Or both 1 and 2 is the same thing?
1
vote
2answers
164 views

Slowing down high energy neutrinos?

Which atoms can slow down high energy neutrinos? I mean in which medium high energy neutrinos will tend to slow?