Scalar quantity which is the magnitude of velocity.

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2answers
1k views

Calculate speed from accelerometer

I am trying to use my accelerometer on my mobile device (smart watch to be specific) to calculate a persons arm swing speed. The data returned from the accelerometer is in $m/s^2$. Since the ...
0
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1answer
27 views

Calculate constant acceleration for a length of track with start at rest and final velocity known [on hold]

My maths and physics are rusty... I'm a bit ashamed, but I have this problem: Let's have a 1000m linear accelerator (mass driver) propel a payload at constant acceleration, with a final velocity of ...
-3
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3answers
47 views

Does Size affect Distance covered at constant speed? [on hold]

How does size of an object affects its speed? Suppose if two objects of different sizes (very different indeed) moves at speed of say 100 mph for an hour, will the object greater in size covers the ...
4
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2answers
203 views

Light wave crossing media and the relationship between speed, wavelength, and frequency

There are many threads on this topic (like this one) but one aspect about the equation $ v = \lambda\nu $ still confuses me. I have read that frequency does not change when light crosses into ...
2
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3answers
41 views

How to figure out the height it would take for an object to reach terminal velocity?

I'm trying to figure out how high an object would have to be dropped to reach it's terminal velocity. Specifically if an object had a terminal velocity of 520 mph, how would I figure out how high it ...
0
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3answers
54 views

How to tell if area is displacement or distance?

why is it not called "velocity v. time"? how do you know? If the y-value can be either positive or negative, the direction is then indicated. i think this is why it should be called velocity but ...
3
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1answer
50 views

Mechanical waves with slower speed than sound

Sound is mechanical waves of high and low air pressure transmitting with 300m/s. Are there high and low air pressure waves transmitting with lower speeds? How are they produced?
18
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5answers
4k views

Why is there a controversy on whether mass increases with speed?

Some people say that mass increases with speed, some people say that the mass of an object is independent of its speed. I understand how some (though not many) things in physics are a matter of ...
0
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2answers
40 views

Packets of information in the real world

Please excuse this apparently naive question. no one appears to have the answer. If a standard packet of data is travelling down a standard fibre, what is the physical time taken between the first ...
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2answers
60 views

Is escape velocity really a velocity?

The term escape velocity is quite common to us. But we know velocity is a dimension dependent on the direction. But the escape velocity has same value irrespective of from where it is thrown from the ...
0
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2answers
35 views

Why can't we increase the speed of sound in a constant Temperature-pressure condition?

We know the speed depends on the kinetic energy. Imagine that we have 3 iron balls equally spaced and kept in space (zero gravity condition). If i push the first ball slowly it would travel slowly ...
0
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1answer
52 views

Change of direction in physics when an object in motion stops

Consider an object moving with an acceleration $a = -1 \text{m/s}^2$ starting with speed $v(0) = 4 \text{m/s}$ towards east and stopped after 4 seconds. (There are no friction.) After 4 seconds, the ...
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3answers
118 views

Speed as the fifth dimension

In spacetime there are four general dimensions, three of space and one of time. Why is it that other dimensioned qualities seem to be rarely considered as part of spacetime? For example, why isn't ...
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3answers
5k views

Does friction decrease as objects move faster against each other?

I was told that the faster two objects move against each other, the less the friction between them would be… compared to if they were moving slower. So does friction decrease when the body is moving ...
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7answers
8k views

I need help with finding distance traveled

How do I find the distance traveled of an object if the speed is not constant?
0
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3answers
109 views

The relation between mass and speed

Massless particles (or luxons) have no (rest) mass ($m = 0$) and a speed equal to the speed of light ($v = c$). Massive particles (or bradyons) have mass ($m > 0$) and a speed lower than the speed ...
2
votes
2answers
87 views

Sounds of supersonic objects

Would you, as a stationary observer, hear a sound in reverse when the source of the sound travels with twice the speed of sound? Of course, he wouldn't hear anything at all before the airplane passed ...
0
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3answers
104 views

What is the pace of absolute time

How fast or slow compared to my alarm clock time does time passes in a place where there is no gravitational pull and where you are not moving. I don't know if my question is clear, but is there some ...
2
votes
3answers
2k views

Wind effect on driving a ground-based vehicle

A friend of mine seems to think that wind affects the ground-speed of a ground-based vehicle in the same way airspeed affects an airborne aircraft. i.e. If faced with a 10mph headwind, your car isn't ...
4
votes
5answers
1k views

I know light's speed in vacuum is constant, but what about its velocity?

Is the velocity of light in vacuum constant? It seems it would be different depending on whether it is coming toward you or away from you, but I just want to make sure. Does the direction of light ...
1
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1answer
61 views

How to calculate distance travelled while car is rolling, given start and end speed?

I'm trying to calculate the distance travelled by my Formula Student racecar if it starts at a certain speed, goes into Neutral (no acceleration, no brakes, just rolling on its wheels), and ends at ...
1
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1answer
48 views

Warship cannons influence on speed/direction [closed]

I've been looking at great warships like the Iowa or equivalent ww2 warships, and I raised question. This kind of war is pretty much only about strategic placements, accuracy and fire power. Hence ...
3
votes
1answer
58 views

Can a “flat function” be a particle trajectory? [duplicate]

Recently I came across the concept of a flat function, which is a smooth function $f:\mathbb{R}\to\mathbb{R}$ all of whose derivatives vanish at a given point $x_0\in\mathbb{R}$, the canonical example ...
0
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0answers
29 views

How do scientists measure miniscule constants like the mass and charge and speed of an electron?

What can measure the extremely tiny mass of an electron? Is it through indirect means? The same goes for charge. The pull of a single electron must be infinitely small. And if one is to attempt to ...
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3answers
85 views

Speed of heat / quantification of heat and other magnitudes

Is the speed of heat infinite? When solving the heat equation in a semi-infinite bar, we can see that a pulse in the finite end draws an immediate change in every point of the bar. So, at any given ...
12
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5answers
5k views

Why and how does negative velocity exist?

Why and how does negative velocity exist? I have read on the internet about negative velocity but I still don't understand how it can even exist since time is positive and so is length. By doing some ...
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1answer
32 views

Moving objects along a radius

I'm working on a project involving a Roomba which I'd like to move precisely from coordinate to coordinate. To move the Roomba manually you need to give it a velocity between -500 to 500mm/s and a ...
3
votes
1answer
71 views

Are moving objects producing stronger gravity fields? [duplicate]

If the strength of gravitational influence exerted by a body is derived from its mass and energy then is it true that a moving object which has some kinetic energy should also produce stronger ...
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3answers
134 views

What is the physics of traffic speed limit? [closed]

In my highschool class the teacher said that the speed limit is designed to prevent drivers from crashing. Does anyone know how they are able to determine the speed limit?
0
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0answers
22 views

What type of relationship should the speed of sound vs. air temperature graph have? Linear? Quadratic? Exponential? [duplicate]

I did a lab in class and the data I got might be a bit skewed (this is homework). When I graphed the speed of sound (m/s; y-axis) vs. air temp (degrees Celsius; x-axis), my graph resembled that of the ...
0
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1answer
145 views

Analytical Mechanics [closed]

I see that $W_a(1) = \dot U_a(1)=\ddot{X_a}(1) = 0.3 $ Since $U_{O'}=0 $ then O' is Instant centre of rotation. Then $U_b = 2U_a = 0.6$ I tried a lot, about a week, i find the speed, but there ...
0
votes
1answer
33 views

Kinetic Energy - use a log scale or not? [closed]

Lets say we have a series of balls and an eggs. All items have equal mass but are traveling at different velocities. Thus they have differing kinetic energies. Now, for each 'ball' object we have, ...
1
vote
2answers
120 views

Why can velocity and acceleration be negative?

Why is speed and acceleration negative when $V_1$ of an object is say 150m/s, $V_2$ is 0 m/s and $\Delta d=0.50\,\rm m$? I found the time it takes which is 0.0033s and the acceleration to be 90909.09 ...
3
votes
1answer
303 views

Calculating Kryptonian speed in the movie “Man of Steel”

This is my first question, so I'm not sure if this is the right place to ask but: How would you go about calculating the speed of Kryptonians in the movie Man of Steel (2013)? Specifically, I'm ...
0
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2answers
491 views

Why does time exist? [closed]

So I have been thinking about some subjects and one of it involves time. And I tried writing a story/question on here to summarize the bigger picture but it's not going to happen it's too complicated ...
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votes
3answers
62 views

How to calculate meters per second speed when i have distance in meters and time in minutes [closed]

It might be a simple formula but I want to confirm it so can you please tell me how can I find speed in meters per second when I have Distance = 7720298 meters and total time 320941.03 minutes. How ...
0
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0answers
50 views

Speed of light, comparison of two light waves travelling side by side

okay so.here is setup of my question...say we have two observers A and A'..A is fixed to origin of coordinate axis x,y while A' is inside a hollow box (shown as rectangle MNRP) whose one side MN has ...
0
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2answers
59 views

Speed to power conversion

Here it is stated that there is a cubic relationship between fan speed and power consumption (Pfan ∝ FanSpeed^3). I have the fan speed (m/s), but I need to convert it into power (W). How can I compute ...
0
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0answers
22 views

In Which Position A Co-passanger should Sit On A Turning Bike

Pardon me for this very basic mechanical science question. But I just want to clear my doubt it. Whenever I sit a behind someone on a bike I get confused when the the bike has to take a sharp turn. I ...
3
votes
1answer
46 views

Why do you seem to go faster as you hug a turn?

I was driving to work this morning when this question occurred to me. I was going up a clover-leaf entrance ramp to the highway. The person in front of me was lazily floating the outside of the curve, ...
88
votes
16answers
23k 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 ...
0
votes
3answers
7k 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, ...
5
votes
3answers
141 views

Are there any natural phenomena on Earth that involve supersonic speeds?

Are there any natural phenomena on Earth that involves supersonic speeds, other than volcanic tephra and meteoroids? Edit: By natural I mean not man made like airplanes, rockets, missiles, bullet, ...
0
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2answers
138 views

What is third cosmic velocity?

I have been studying Gravitation chapter and there I found one term : Third cosmic velocity which is also known as interstellar speed. So what is it ? What it really tells about? I tried to gather ...
0
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0answers
26 views

Why does kinetic energy quadruple when speed doubles? [duplicate]

Why does kinetic energy quadruple when speed doubles? Please explain (in simple terms) with examples if possible.
4
votes
1answer
116 views

You are trapped on a frictionless sheet of ice. Can you escape by inhaling in one direction, then exhaling in the opposite direction?

You are trapped on a frictionless sheet of ice. If you trued to escape by blowing, you would have to inhale eventually, which would counteract the force you gained by blowing. However, if you were to ...
3
votes
3answers
173 views

Does my (too low) tire pressure, affect the speedometer of my car?

Does my (too low) tire pressure, affect the speedometer of my car? How big is this effect?
1
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1answer
31 views

Speed formula intuition, dividing distance by time

I have a vague intuition as to why speed is distance / time, but mathematically speaking I don't understand the division aspect of it. One of the first things I learned in arithmetic was that you ...
1
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1answer
214 views

Difference between Speed and Velocity

What is the difference between Speed, Velocity and Acceleration? Could any one describe it pictorially?. I am more over confused even after investigating many times. I am unable to relate myself ...
5
votes
3answers
2k views

How to relate speed of sound with relative humidity?

I am exploring the idea of measuring the humidity of a space using sound waves, however I am having trouble finding a mathematical relationship between the speed of sound and the humidity level. ...