In everyday use and in kinematics, the speed (commonly referred to as v) of an object is the magnitude of the rate of change of its position with time or the magnitude of the change of its position per unit of time; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero.
Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour (km/h) or, in the US and the UK, miles per hour (mph). For air and marine travel the knot is commonly used.
The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in a vacuum c = 299792458 metres per second (approximately 1079000000 km/h or 671000000 mph). Matter cannot quite reach the speed of light, as this would require an infinite amount of energy. In relativity physics, the concept of rapidity replaces the classical idea of speed.
If I have a 7.5HP motor running at 1750rpm with a pulley and v-belt and connect it to a gearbox, where the right angle worm gearbox sees an input speed of 580rpm, how would I go about sizing the gearbox?
Am I correct to say that I would size the gearbox for the lower input speed and more...
A particle without mass is supposed to travel at speed of light.
But isn't it that a photon has no mass but has relativistic energy.. therefore why does it travel at speed of light.. or perhaps if a photon had no relativistic energy.. it would travel a bit faster than the current lightspeed?
How much pressure in PSI would it take to generate 150mph stream out of a 2 mm perfectly round orifice? And how many GPM would that equate to? Thanks for any help
Homework Statement
In a report I am asked to assess the speed of response of various systems, however I am not exactly sure what this means, be great if someone could explain
The Attempt at a Solution
Step response plots were produced for each simulation and MATLAB was used to assign...
Homework Statement
When a soccer ball is kicked toward a player and the player deflects the ball by "heading" it, the acceleration of the head during the collision can be significant. Figure 2-38 gives the measured acceleration a(t) of a soccer player's head for a bare head and a helmeted head...
10 seconds somewhere can be one on Earth due to time dilation, right? So In the case of distance wouldn't light have traveled more than 186,282 MPS since it had 10 seconds to travel relative to the 1 second on earth. So if light traveled at 186,282MPS for 10 seconds it would have traveled...
Homework Statement
A satellite is in a circular orbit (radius R) around a planet of mass M. To change the satellite's orbit the engines fire and its speed is suddenly doubled. The engines fire for a very short time. Determine the length of the semi-major axis of the new orbit.
Homework...
Homework Statement
A train speeds past a pole in 15 seconds and a plate form 100 m long in 25 seconds. Its length is :
Homework EquationsThe Attempt at a Solution
x/15 = (x+100)/25
after solving this equation
x= 150.
but the ans is 180 m ? what should be the correct ans.
Homework Statement
Hello, I havre problem here relevant to an image I will attach.
''A cricket ball hit by a batsman moves with a speed of 6m/s along a straight line path PQRS, as shown in the diagram. When the ball is at R, a fieldsman starts to run in a straight line from T with a speed of...
The question:
If the max speed I can go in the universe is the speed of light measured from?
Background:
If there are three rocks in a vacuum along a line (the x axis), one is stationary (rock 1), one is moving 5 m/s in the x direction (rock 2) and one is move -5 m/s in the x...
Homework Statement
If a spacecraft is traveling to a star which is located at a distance of 1 lightyear and it would take the spacecraft 1 year to reach the star in its own frame, how fast would the spacecraft actually fly? Also, how long would the journey take for an observer on Earth...
Hello everybody!
For my water in nanoscaled-pores simulations with SPH I need a value for the characteristic velocity.
My planned approach is to estimate this value by attaining the propagation speed of a diffusion wave.
But I have problems with understanding this process since I find some...
I am having trouble understanding tangential speed as it applies to uniform circular motion and I would appreciate any help.
Say I have a ball on the end of a string that I hold with my hand and rotate at a constant speed. If the string provides the centripetal force and acceleration, where...
Homework Statement
14.34 The 0.5-kg bob of the pendulum travels a complete circle about the pivot
point O. Determine the smallest possible speed of the bob in position A if it is
suspended from (a) a rigid rod of negligible mass; and (b) a string
Homework EquationsThe Attempt at a Solution...
Homework Statement
A current of 1600A exist in a rectangular (0.4 x 16 cm) bus bar. The electrons move at an average velocity of v. If the concentration of electrons is 1029 per cubic meter, and they are uniformly distributed, what is v?
Knowns
Current (i) = 1600A = 1600 x 1018 aA
Charge per...
Homework Statement
The speed of a runner increased during the first three seconds of a race. Her speed at half-second intervals is given in the table. Find lower and upper estimates for the distance that she traveled during these three seconds.
It follows the image's square.
Homework Equations...
This problem bothered me many years ago when I was taking a university course in
quantum mechanics, but I assumed it was due to an error on my part which I, however,
couldn’t locate, and I didn’t ask my course instructor about it. Recently, when
researching a q.m. question on the Internet...
The two spaceships A and B approach each other at constant speed v:
A----------B
There is no way of knowing if B is standing still while A is moving at speed v (to the right), or if A is standing still while B is moving at speed -v (to the left).
This shows that speed is relative.
But if the...
In school, I was taught that the position of an electron relative to the nucleus is only an approximation. It is very likely that the electron will be close to the nucleus and where it is 'expected' to be, but it may in fact be anywhere in the universe.
Is this correct? And does this allow...
So I followed the derivation of the Macroscopic Maxwell's equations by averaging the fields / equations and doing a taylor series to separate the induced charges and currents from the free ones. But why does light now "suddenly" travel slower in dielectric media? I mean, sure, it comes out from...
At supersonic speed, air become compressible. However why does Mach number decrease when flow area decrease? I understand that pressure will increase because the density will increase when flow area decrease. However shouldn't the Mach number increase in order to conserve mass flow? Unless the...
Sorry, me again. In another thread #47 I gave a experimental setup to detect an anisotropy in light speed of the form ##c(\hat{n}) = c_o + \alpha (\hat{n}\cdot\hat{v})##. It was pointed out quite correctly that the error incurred in the long arm to the sensor would cancel the anisotropy making...
Homework Statement
I am having difficulty understanding the conversion between power and rotation at the engine and at the wheel. Can you please state which parts are right and wrong, and why please as I think I've spent that long on researching I've confused myself with too much information...
Has anyone encountered the term "hypersonic sound speed" in connection with fluctuations of thermodynamic quantities in condensed matter? How is hypersonic different than regular sound?
Is there any relationship between the Speed of gravitational waves and the Universe's "local" expansion rate?
Speed of gravitational waves is supposed to be equal to the speed of light. Gravitational waves don't travel faster than light.
But we can observe far galaxies moving away from us with...
Homework Statement
Homework Equations [/B]
Equations of motion:
v = u + at
s = 1/2 (u + v) t
s = ut + 1/2at^2
v^2 = u^2 + 2as
3. The Attempt at a Solution
Hello, on a i used the 2nd equation:
30m = 1/2 (3*10^8m/s+3*10^8m/s) t so -> t = 1*10^-7s
but to get the correct solution i...
$\text{A person jogs eight complete laps around a $400 \, m$ track in a total time of $14.5 \, min$}. \\$
$\textit{a. Calculate the average speed in $km/h$}\\$
\begin{align*}\displaystyle \frac{(8)400 \, m}{14.5 \, min} \left(\frac{km}{1000m} \right) \left(\frac{60 \, min}{h}...
Hi,
What is people measuring when they measure the speed of light (c) actually? the photons or the waves? or some kind of manifestation of light?
I ask because I was reading about photons and that they "might" have a very small mass and therefore are not traveling at c. If photons have a...
Homework Statement
Homework Equations
E = γmc2
p = γmv
K = E - mc2
E2 = c2p2 + m2c4
The Attempt at a Solution
I have completed most of this question, but I am struggling to get the required result to the final part of the question.[/B]
Good morning.
I've just completed working through Einstein's work on special and general relativity. Do I understand that, in relativity, a moving object cannot measure its own speed without an external reference to compare to? IE, there is no experiment it can conduct to determine its own...
Homework Statement
Homework EquationsThe Attempt at a Solution
When the source is not moving, ## \lambda = 6250 A ## ...(1)
When the source is moving, ## \lambda ' = 6500 A ## ...(2)
From (1) and (2),
## \lambda ' > \lambda ## ...(3)
This means that the source is moving away from...
1.Why does the angular speed of small gear depend only on larger gear only?
2.Why does the length of linkage connecting two gears does not have any influence on the angular speed of smaller gear?
The first question can be answered by looking at slack and tightening of chain caused by rotation...
A cart which weighs 500g is moving on a horizontal table with the starting speed of 7 m/s. At the end of the cart there's a non-elastic wire attached, which is thrown over a pulley, and on the other end of the wire there's a 200g load. I need to find the speed of the cart and the distance it...
I have two pressure vessels (volumes known) at different pressures (known) . There is a connecting tube between them of known diameter. I first want to calculate velocity during the equalization and should easily be able to determine the time to equalization. P1 V1 P2 V2 Cross section of...
I've learned that ideal gases have the same average kinetic energy, but this doesn't necessarily mean that they have the same speeds within a container..Instead, is it right to say that (according to kinetic molecular theory) that the speed of molecules at an instance is a wide range of speeds?
If the speed of light is ~300 m/s in a vacuum, can the electric and magnetic fields of the wave be condensed such that it travels faster? The idea being that an outside force condenses these fields and lenghtens the wavelenght with no loss of energy thus increasing the directional speed. The...
Homework Statement
If the car is going 30 m/s half way up the loop and loses energy due to friction at a rate of 2.0J per meter of track, how fast will it be going at the top?
(this is question related to the loop of roller coaster track, with radius 20m.)
Homework Equations
1. Ki + Ui = Kf +...
Why the speed of light is constant for every observer ? Is it a special thing for photons cause I guess there's no other elementry particle that can move with c ?
Also I want to investigate the constant of c for every observer, in the perspective of particle relationship.
For example, can I...
Hi there, so I want to know how to get the speed I need to move some object from point A to B, accordint to the distance between points, gravity and height angle.
I means, I have this:
height angle = 40.0
distance from point A to B = 5m
gravity = -9.81
speed = ?
I think that I just need to know...
Homework Statement
An object of mass 100kg is acted on by a constant force as it moves through a displacement at a constant speed of 7.2m/s. What is the net work done on the object?
Homework Equations
Wnet = ΔK
Fnet = 0
The Attempt at a Solution
I know that the answer is zero because the...
Homework Statement
14.11 A boy slides down a water chute, starting from rest a A. Neglecting friction
determine his speed (a) at the end B of the chute; and (b) on entering the water at C.
Homework EquationsThe Attempt at a Solution
for (a):
for (b):
Do I have to treat the boy at B as...
Hello, so i know in a free fall the acceleration is constant (9.8 m/s2) therefore speed/velocity is increasing.. But I am wondering why we can't use Speed=D/T
Homework Statement
The lawn tractor in figure 18 goes up a hill at a constant velocity. Calculate the power that is developed by the tractor.
Mass: 120.0 kg
Angle of incline: 21 degrees
Distance: 12.0 m
Velocity: no velocity given other than it is constant
Time: idk
Homework Equations
None...
Homework Statement
The question and the known/given variables are on the image in part 3. The question says that a 20-g bead is attached to a light 120 cm-long string. Now in my mind the bead will travel in a circular path if it is pushed really hard. So Isn't the length of the string, 120 cm...
Homework Statement
The exercise is this: The mass of the car is m=500 kg. The maximum speed of the car on flat road is v1=35 m/s and on 10 % up hill (tan(alpha)=0.1, alpha is with respect to flat) the maximum speed is v2=20 m/s. The friction force is double on up hill because it has been made...
Homework Statement
What is the escape speed of an electron launched from the surface of a 1.0-cm-diameter glass sphere that has been charged to 10nC?
Homework Equations
Given:
d= 1.0cm
r= 0.05cm= 0.0005m
q1 = 10nC = 10 x 10-9 (sphere)
q2 = -1.6 x 10-19 (electron)
Equation:
U = (kq1q2)/r
KE=...
Homework Statement
A proton is released from rest at the positive plate of a parallel plate capacitor. It crosses the capacitor and reaches the negative plate with a speed of 50,000 m/s. What will be the final speed of an electron released from rest at the negative plate?
Homework Equations...
Homework Statement
A small but very powerful bar magnet falls from rest under gravity through the center of a horizontal ring of conducting wire, as shown in the figure below (on the left). The speed-versus-time graph, in arbitrary units, of the magnet will correspond most closely to which of...
Does centrifugal force generate in increase in overall speed? For example, if I am driving down a highway on-ramp which goes in a circular fashion, with my speed slowly increasing, does my overall speed increase because of the centrifugal force generated from the circular on-ramp? Is more force...
$\tiny{243.13.01.19}$
$\textsf{The following equations each describe the motion of a particle.}$
$\textsf{ For which path is the particle's speed constant?}$
\begin{align*} \displaystyle
R_1(t)&= t^7\textbf{i}+t^4\textbf{j}\\
R_2(t)&= \cos(3t)\textbf{i}+\sin(8t)\textbf{j}\\
R_3(t)&=...