Scalar quantity which is the magnitude of velocity.

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1answer
125 views

Force and Energy in robots

There are two similar and hypothetical robots that move with wheels powered by motors, Robot A and Robot B. Robot A has a gear ratio of 3:1 (The gear connected to the motor is three times larger than ...
0
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1answer
59 views

Can we work out how fast we are traveling by looking at our mass?

If we (the galaxy) were traveling close to the speed of light; relativity says we would need proportionally more energy to go faster. Given that relative to the cosmic microwave background, the Local ...
0
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2answers
342 views

Temperature loss of a moving object

I would like to know how to calculate the temperature change of a moving object. For example if I throw a ball that is warmer than the surrounding air, how much would it lose form it's temperature in ...
2
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2answers
182 views

Effect of position on a motorbike turning

While searching tips for driving a motorbike on wet roads safely, I heard some pilots saying to lean inside the slope makes the bike less tilted, so it's safer. I agree leaning make the bike less ...
0
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0answers
13 views

How to calculate static air temperature

Let's suppose I have an airplane flying at an unpecified altitude and the following data are given: Flight Mach number: $M=0.76M$ Ground speed: $v_{kts}=470kts$ My goal is to estimate the air ...
2
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4answers
8k views

Does inertia increase with speed? [duplicate]

I have heard that when the speed of the object increase, the mass of the object also increase. (Why does an object with higher speed gain more (relativistic) mass?) So inertia which is related to ...
0
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1answer
54 views

Does adding mass to the fan blades affect its max velocity?

If I replaced fan blades with congruent blades, the only difference being the second set has a higher density, would that affect the speed cap on the spin? I know it would affect acceleration, but I ...
44
votes
6answers
3k views

The speed of sound is a single value yet the speed of atoms is distributed over many values. Does the sound wave front smear out?

Sound waves travel with constant speed, but air molecules that transfer action move with different speeds than the ones described by Maxwell distribution. Why does the sound wave not smear out and ...
4
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6answers
6k views

Force required to drive car

From what I know of Newtonian Mechanics, if an object is moving at a constant velocity, the net force acting on that object is equal to zero. If there is friction, then the applied force required to ...
2
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2answers
109 views

Submerged water jet

I am trying to calculate at what pressure and speed water from a high pressure water jet will hit an object 100 millimeters away from the nozzle opening, but i can't figure it out. The nozzle will ...
0
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1answer
25 views

How does atmospheric pressure affect the speed of object?

I was reading things about the Hyperloop One start-up project ( https://hyperloop-one.com/what-is-hyperloop) and I couldn't get any details on how the process works. This is a new transportation type ...
9
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1answer
17k views

How fast would someone have to run to run over water?

I was thinking about Flash, the superhero, or the little boy in the Incredibles. There is one Yahoo answer that doesn't answer a lot. Especially, I don't think surface tension would help a lot for a ...
1
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3answers
79 views

Air flight and Earth's rotation

I read a response asking why flights of equal distance east and west take roughly the same time (disregarding wind actions). I have trouble visualizing part of the answer; "the speed of the rotation ...
0
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0answers
29 views

Is there a physical formula or equation to describe change in size of rotating tire?

I've heard that tires will actually grow larger when you are moving, and shrink back down when you stop. I was wondering if there is a way to calculate the size of a given tire, and what the variables ...
1
vote
0answers
14 views

White cloud around fighter jet at Supersonic speed [duplicate]

When a fighter jet flies with Supersonic speed then some type of white cloud form around the fighter jet for short period of time.what is the reason behind this phenomena?
5
votes
2answers
9k 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
votes
1answer
219 views

Explanation about friction force directions of two moving bodies in contact

can someone explain me why in this scenario (picture below) we have a friction force Ftr12 in the same direction as movement (left part of the picture, case 1 ) and how these directions of friction ...
0
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2answers
39 views

Wheel versus Sphere: Traveling Linearly Down a Track

Assume the following: A tire-like wheel and sphere are both of diameter d and mass m They are both made of the same material They are both resting at the apex of an inclined track An equal amount of ...
3
votes
1answer
67 views

Fastest Speed of Sound

Obviously, sound (like every other causal phenomena) may not travel faster than the speed of light. I know that materials with a high bulk modulus and low density will typically have faster speeds of ...
-2
votes
3answers
44 views

Concequences of the speed of light beeing absolute? [duplicate]

If photons have a speed limit (speed of light), what happens when you shoot photons through a flashlight but you yourself already have some speed? Do the photons from the flashlight only travel at [...
0
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2answers
4k views

What does a speedometer measure?

When speaking of the velocity of a particle, we must specify a reference point. The same holds when we talk about the speed of a particle (is this correct?). If so, a speedometer measures instaneous ...
0
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2answers
69 views

Is there a way to make atom move faster without heating them?

The more heat you add the faster the atom will move. This is something that is common knowledge. My question is it possible to make the atoms in let's say a gas move faster without adding heat of a ...
-6
votes
1answer
51 views

Can velocity be negative? [closed]

In free fall I use the formula V=g*t and g is negative(-9.8m/s^2). It gives me negative.
0
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0answers
42 views

According to the theory of relativity, (relativistic) mass of an electron changes when it moves at very high speed; how and why? [duplicate]

It is given that $$ \mathbf m' = \frac{m}{\sqrt{1-\frac{v^2}{c^2}}} $$ How does (relativistic) mass change here?
5
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1answer
273 views

Are we traveling through time at the speed of light? [duplicate]

In the image below the y axis represents time and x represent velocity. Point D represents velocity c, point E represents 1 second per stationary observers second. What this chart is showing is as you ...
-3
votes
1answer
98 views

Calculating speed in four dimensions [closed]

If you are moving at $c$ in 3D space and $c$ in time axis too, What would be your total speed? Edit: Since question has been voted to be closed, I shall make an Edit. In 4D world all objects move ...
3
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2answers
242 views

Distance and Speed

When I look up in the sky and I see a plane moving and it's further away why does it seem to move so slow compared if a flock of geese flies over at same time and seems to travel faster?
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2answers
47 views

Speed of Sound in matter

So basically when it comes to the speed of sound, it is said that speed of sound in media is based on two main factors - 1)elasticity and 2)density from the formula V= $\sqrt{E/\rho }$ where E is ...
5
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0answers
50 views

What is the max frequency of sound in a given medium?

When talking about acoustic waves, medium continuity (pressure, density) is implicit. But can the wavelength of an acoustic wave be as small as intermolecular separation? For example, can ~10 THz ...
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votes
3answers
1k views

Speed of an object in air versus in vacuum

Okay, imagine that you are shooting a rocket down a tunnel that is 60 miles long and the rocket is travelling at 60mph, so the rocket should reach the end of the tunnel in a hour, right? Yep, in an ...
5
votes
3answers
547 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 ...
0
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0answers
15 views

What is the speed of transferring of energy in an inelastic solid? [duplicate]

Assuming that there is an inelastic, very low mass, very long, solid rod which is 150 million km long. This distance requires approximately 8.333 minutes for light to travel. If I apply a force at one ...
-1
votes
2answers
87 views

What particles travel near the speed of a photon? [closed]

I know photons travel at the speed of light. How does the size of a particle determine its maximum velocity? Phonons, Preons, Electron ect. Is there a scale in from the smallest particle's maximum ...
1
vote
3answers
33 views

Phases and sinusoidal waves

When we're talking about a wave, just a singular sinusoidal wave, what exactly is a 'phase'? I came across a question that gave values of frequency ($550$Hz), and speed ($330$m/s). The question then ...
127
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17answers
33k 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 $\frac{1}{2}mv^2$. Why does this not increase linearly with speed? Why does it take ...
0
votes
2answers
32 views

How to calculate the acceleration, if the mass-center is not on the force-vector's line (2D)

In a 2D plane there is an object, whose center of mass is at the $P$ point. The mass of the object is $m$. We apply a force $\vec F$ at the point $A$. If the center of mass is on the line, defined ...
0
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2answers
46 views

How to calculate the maximum speed of an object?

There is a spaceship, whose mass is $100 \, \mathrm{kg}$. The thrust of its rocket is $300 \, \mathrm{N}$. How is it possible to calculate the maximal speed that the spaceship can reach, and the time ...
1
vote
1answer
52 views

The Energy Equation

I've been studying the energy equation in relativistic motion $E= \frac{mc^2}{\sqrt{1-v^2/c^2}}$, which can be expanded as $$E = mc^2 + \frac{1}{2} mv^2\text{ + some other terms.}$$ I'm curious ...
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2answers
46 views

can time dilation be used to determine if an object is moving

I know that movement is only relative to another object, but as you move faster you also experience time dilation, correct? So if one body is moving faster then it should have a dilation of time, ...
7
votes
7answers
771 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 ...
1
vote
3answers
346 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 ...
0
votes
1answer
27 views

Would a bullet damage a piece of metal the same as a pointy stick?

If you used a materials that would offer zero bending or dulling (the bullet/ pointy stick), would a 10 g bullet traveling at 1000 m/s with a surface area of 1 mm squared damage a piece of metal the ...
4
votes
1answer
1k views

How fast would an object have to move to create a vacuum behind it?

When an object moves, I assume that the air above it, instead of remaining at the same general height, is pulled downward as it is passed in order to fill the low-pressure area behind the object where ...
1
vote
1answer
59 views

Can Doppler Shift be used to calculate speed of an observed object?

Thanks for looking. Just musing over an idea this afternoon: if I had a radio controlled plane, I could obviously calculate its airspeed based on pings and the known speed of sound if it was ...
6
votes
1answer
666 views

Liquid wave faster than sound in the above gas: possibility implications

I recently heard that tsunamis (meaning "harbour wave") can travel over 800 kilometres per hour (500 mph), not so far from the speed of sound in the air. May it happen, in general, that a wave in a ...
0
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0answers
21 views

Force by torque or force by speed with make the body jump?

I have a small object made of plastic weighing 3kg and I want to make it jump with the help of a dc motor and a plastic rod attached to it (4 such motor with rod are attached on the object at 4 ...
4
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2answers
194 views
2
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3answers
3k views

Fuel usage at the same constant rpm at different gears

I've had a discussion with my father today, about the fuel usage of a vehicle at the same rpm, but a different gear. He claims that the following situations have the same fuel usage: ...
7
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5answers
4k views

Maximum speed of a rocket with a potential of relativistic speeds

Ultimately, the factor limiting the maximum speed of a rocket is: the amount of fuel it carries the speed of ejection of the gases the mass of the rocket the length of the rocket ...
30
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9answers
7k views

What is the speed of the fastest moving body in our solar system?

On Wikipedia I saw that the average orbital speed of planet Earth around the Sun is a whopping $29 783\text{ m/s}$, and it made me wonder are there bodies (planets, meteorites, asteroids) that move ...