What is Train: Definition and 649 Discussions

A train is a form of rail transport consisting of a series of connected vehicles that generally run along a railroad (or railway) track to transport passengers or cargo (also known as "freight" or "goods"). The word "train" comes from the Old French trahiner, derived from the Latin trahere meaning "to pull" or "to draw".Motive power for a train is provided by a separate locomotive or individual motors in a self-propelled multiple unit. The term "engine" is often used as an alternative to locomotive. Although historically steam propulsion dominated, the most common types of locomotive are diesel and electric, the latter supplied by overhead wires or additional rails. Trains can also be hauled by horses, pulled by engine or water-driven cable or wire winch, run downhill using gravity, or powered by pneumatics, gas turbines or electric batteries.
The track usually consists of two running rails with a fixed spacing, which may be supplemented by additional rails such as electric conducting rails ("third rail") and rack rails. Monorails and maglev guideways are also occasionally used.Passenger trains include passenger-carrying vehicles and can often be very long and fast. High-speed rail systems began expanding rapidly in the late 20th century, and this remains a major subject of further development. The term "light rail" is sometimes used to refer to a modern tram system, but it may also mean an intermediate form between a tram and a train, similar to a heavy rail rapid transit system.
Freight (goods) trains use freight cars (or wagons/trucks) to transport goods or materials (cargo). It is possible to carry passengers and freight in the same train using a mixed consist.
Rail cars and machinery that are used for the maintenance and repair of tracks, are termed "maintenance of way" equipment; these may be assembled into maintenance of way trains. Similarly, dedicated trains may be used to provide support services to stations along a train line, such as garbage or revenue collection.

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  1. D

    Throwing a ball out of the end of a moving train

    Let's say there is a train moving at 50 mph on the moon on a flat surface (say it's a perfect vacuum) and you are on the last cart where you throw a ball out the rear in the opposite direction the train is moving (directly away from it, parallel to the ground). The ball thrown is also...
  2. U

    B Train traveling near light speed

    A train is traveling around the Earth at just under light speed. Light would circle the Earth around 7 times per second so let's say this train cricles the Earth 6 times per second. There is a physical ticker on the track of the train that records revolutions. Each time the train makes one...
  3. K

    Show that the flywheel inside the train counteracts lean in a curve

    Summary: Consider a train carriage rolling along a curve that forms a left turn on the track. The carriage speed is directed along the y-axis (into the plane of the paper) in the figure. The trolley will have a tendency to curl in the curve in the specified direction. A flywheel is inserted...
  4. tholepin

    I'm attempting to train a quantum dog (Rusty), suggestions?

    I'm attempting to train and interact with a quantum dog named Rusty. Any and all suggestions are or aren't appreciated.
  5. A

    I Special Relativity: Train in Tunnel Paradox Solved

    Hello, I was wondering if anyone could set up and solve a classic train in a tunnel paradox from special relativity with unique values for multiple observers including time space diagrams. Thanks
  6. U

    B Train platform -- light speed and time quandry

    Summary: how can a train traveling at light speed, travel at two different speeds being the same train, depending upon whether you are on the train platform or in the train You say good bye to your friend at the train station. You get into train that will travel at just under light speed...
  7. B

    I Problems with Einstein's 1920 "Relativity"

    Hi, I have been reading and watching a lot of physics lately but I have come across this problem. I have the basics of special relativity down, and it all seems clear to me. This is not in question to me. For example, I am reading a book on string theory by Brain Greene, and in it he covers...
  8. D

    B Einstein's Train Thought Experiment

    So I got this from an article on wikipedia that covers Einstein's train thought experiment: A popular picture for understanding this idea is provided by a thought experiment similar to those suggested by Daniel Frost Comstock in 1910[13] and Einstein in 1917.[14][12] It also consists of one...
  9. J

    B Twins Paradox: Dropping a Ball from a Moving Train

    Hi guys, I have read about these twins where one of them stayed on the Earth and the other traveled with a rocket. So I thought about the other case where a person stays on the trains station and the train is passing by with a near speed of light - if the guy in the train drops a ball on the...
  10. W

    Train collision (linear kinematics)

    Homework Statement A passenger train is traveling at 29ms^-1 and a freight train is traveling 360m ahead of it at 6ms^-1 in the same direction on the same track. The driver of the passenger train has a reaction time of 0.4s before he starts decelerating. What is the minimum deceleration to...
  11. opus

    Train collision prevention problem

    Homework Statement When a train traveling at 161 km/h rounds a bend, the engineer sees that a locomotive has entered onto the track from the side and is a distance D=676m ahead. The locomotive is moving at 29 km/h. The engineer of the high speed train immediately applies the brakes. What must...
  12. A

    Does the distance between substations affect the efficiency of electric trains?

    Every time I take a train I sort of think about this, so the electrified overhead wire (DC or AC) and the rails form a transmission line and the train is a load that moves along the transmission line. Let's talk about the DC case as it seems more simple, so when the train is at or near a...
  13. W

    I Simultaneity on a moving train

    Question from non-physicist. Hope there is a simple answer. In Einstein's thought experiment with moving train and embankment: If there is an observer in the middle of one of the train cars and one light beam is flashed from inside each side of the car (same location on each sides) towards the...
  14. JD_PM

    Conservation of Energy and Angular Momentum in a Rotating Train-Disk System

    Homework Statement [/B] A train stands in the middle of a rotating disk with an initial angular velocity of $\omega_i$. The mass of the train is m and the moment of inertia of the train-disk is I. At one point the train departs on a straight track to a distance R from the disk's centre. (R...
  15. H

    Calculating the final velocity of a simple electric train

    I am currently in grade 12, and for a physics project (a huge project, which gets assigned to you at the start of the semester and needs to be completed just before exams. You think up your project, make a proposal for it and you prove your hypothesis to be right after a presentation and lab...
  16. TheQuestionGuy14

    B Einstein's train and simultaneity

    [Moderator's note: Spin off from previous thread: https://www.physicsforums.com/threads/is-the-andromeda-paradox-accepted-in-physics.960861/] There's just one thing I don't understand about all this, Einstein's train thought experiment. It basically states that an observer in a train moving...
  17. J

    What velocity does a train need to go up and down the hill

    Homework Statement There is a train of length d and speed v. It is heading towards a hill with height h and length of each side l. What velocity requirement must be met so that the train can go up and down the hill? Homework Equations Ek=m⋅v2/2 Ep=m⋅g⋅h The Attempt at a Solution I'm basically...
  18. A

    Finding friction and tension for a train

    Homework Statement A UTA Trax train engine can apply 96050 Newtons and locomotive has a mass of 1750 kg. The passenger car has a mass of 949 kg. (A) If the train accelerates at a rate of 1.29 m/s/s, how much friction is present in the passenger car? (Assume the locomotive moves...
  19. J

    How Do You Calculate Gear Train Efficiency Based on Load Torque?

    I have been set the following question in my assignment and I have answered all parts with the exception of:- (d) Determine an equation for the efficiency of the gear train in terms of the load (torque) on shaft 2 (all other factors remaining constant). I am struggling here and would appreciate...
  20. Z

    Kinematics Problem: Train braking and blocking an intersection

    Homework Statement A train 400 m long is moving on a straight track with a speed of 21.6m/s. The engineer applies the brakes at a crossing, and later the last car passes the crossing with a speed of 5.0m/s. Assuming constant acceleration, determine how long the train blocked the crossing...
  21. D

    B How does running in a moving train affect race times?

    Property of walking is a constant contact with the surface (base of the train). Property of running is NOT a constant contact with the surface (base of the train). When walking at the same speed we should expect the same result for our hypothetical walker to walk across certain distance (within...
  22. G

    B FTL train + FTL communication thought experiment

    Please move this if it belongs to other subforums. So i thought about some other stuff and then somehow this idea appeared to me, now according to physics it is impossible to communicate information faster than the speed of light through vacuum which is "c". So for any two bodies moving in...
  23. T

    I How to calculate the tractive effort of a train?

    Hi there again, I am trying to correctly calculate the tractive effort pf a train, currently i do this: Power/speedMpS = TractiveEffort I got that from here. But it doesn't provide realistic values, so i am wondering, what is the correct way of calculating tractive effort of a train? Thanks
  24. T

    What does power have to do with the speed calculations of a Train?

    Hi there again, I have been wondering why train simulators(and trains themself) have a kW specification, AND a maximum force indication. If I would calculate the speed of a train using some formula, then where is the power value used for? Does it have something to do? Or is only the maximum...
  25. T

    Where do I find coefficient values for these 2 formulas? (drag coefficients)

    Hi there, So I asked a question here how I would calculate the air drag and the wheel drag of a train and I got an answer that made me very happy. Unfortunately i don't know where i could find the coefficient values required for the formulas. So i am wondering if someone knows where i can find...
  26. T

    Calculating Friction & Air Resistance for a Train Game

    Hi there, I am new here so please don't be too hard on me yet and move this post if i placed it in the wrong forum. I am developing a little experiment game and i want the train to drive using real physics, but I am really bad at physics. So my question is is how do I calculate the friction of...
  27. G

    What happens when you insulate the rails of a DC electric train?

    a DC electric train or tram uses a single overhead wire unlike it's AC counterparts like trolleys which use two, so if there is only a single overhead wire I assume that the return wire or let's call it ground for the electric DC train are the rails correct? Does this mean that it is important...
  28. Claus Berner

    How Does Friction Affect Train Acceleration?

    Homework Statement What is the maximum acceleration the train can achieve? Engine effect=6500kW μ(Friction Coefficient (between rails and wheels))=0.45 g=9.82N/kg m(Train weight)=120,000kg α=0 Homework Equations Fμ=Fn*μ Fn=cos(α)*m*g a=F/m The Attempt at a Solution We've used the equations...
  29. alijan kk

    Is 7.5 Seconds the Correct Time for a Train to Cross a 165m Railway Platform?

    Homework Statement If a train 110 m long passes a telegraph pole in 3 seconds, then the time taken by it to cross a railway platform 165 m long is : Homework Equations The Attempt at a Solution 110 meters/3 seconds = speed of train using this ratio ((110 m)/(3 seconds)) * (110m+165m)=7.5...
  30. alijan kk

    Train Speed: 150m in 25 sec - Find Length

    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.
  31. BWV

    Has anyone tried to train a neural network to learn physics?

    Have been curious about a thought experiment where, given enough experimental data to train, a sophisticated enough neural network / deep learning program could 'discover' most of classical and quantum physics. Any thoughts?
  32. EastWindBreaks

    Minimum number of teeth given the gear train ratio?

    Homework Statement Homework EquationsThe Attempt at a Solution for this class, we were not taught with contact ratio equations, nor the pressure angle is given, so for this type of problems, do we just assume that minimum number of teeth on a pinion will be 12? 3 integer factors of 180 can...
  33. EastWindBreaks

    Simple Gear Train: Pitch Circle Diameter and Typo in Homework

    Homework Statement Homework EquationsThe Attempt at a Solution if you do 38*25/pi , you would get 302.394 for the exact pitch circle diameter, similarly, exact d2 should be 907.183 mm, is it a typo? or did I miss something?
  34. Pushoam

    Distance between train and its carriage

    Homework Statement Homework EquationsThe Attempt at a Solution Let's say that the last carriage gets uncoupled at time t = 0s and at this time the train has moved a distance ##l_0##.The resistive force could be given as ## F_r = AM##, where A is the appropriate constant and M is the mass of...
  35. S

    How to train myself to be more careful?

    I am not a very careful person and I am often overly ambitious. I often think of something that would be cool to have then try to design or build it without considering safety or my abilities. Do you guys know how I could train myself to not be overly ambitious and to be more careful?
  36. E

    A train dragging coal while more coal is added into it....

    Homework Statement A locomotive is dragging empty freight cars, while coal is being dropped into them. It’s falling down into those freight cars with an efficiency (μ). Overall mass of the whole empty train is M. a) Calculate v(t) (velocity with respect to time), assuming that the force of...
  37. D

    B Moving object leaving a train?

    Hello my constituents! Was having a discussion with a coworker of mine and we reached an impasse. If a train is in motion at regular traveling speed, what would happen if a motorcycle were to exit the train while moving? This question presented itself to us in the form of a movie we were...
  38. G

    Train Conservation of Energy Question

    I go to work on the train and I get on at the back and get off at the front. I can choose when to walk through the train. If I walk when the train is accelerating forwards it is harder for me to get to the front and I do more work. If I make the trip when the train is stopped or at a constant...
  39. G

    Train traveling at speed of E field question

    This is a thought experiment so the mentioned values are only for example purpose. I was wondering about an electrical train. So here is the setup, we have rails and an electric train with an overhead wire. In one case the train gets its power from DC and in the other case the train is powered...
  40. C

    Acceleration and velocity: Car and train problem

    Homework Statement A train has a length of 118 m and starts from rest with a constant acceleration at time t = 0 s. At this instant, a car just reaches the end of the train. The car is moving with a constant velocity. At a time t = 14.0 s, the car just reaches the front of the train...
  41. M

    Calculating Train Deceleration: Solving a Homework Problem in 4 Steps

    Homework Statement A person standing on a train platform notices that the first train car, which is approaching the station, had passed him in 4 seconds, and that the second train car passed him in 5 seconds. After this, the front of the train stopped at the distance of 75 meters from the...
  42. J

    Why Do Railcars Use Inverters with Alternators?

    Hi everyone I am currently working with diesel railcars. To power the electrical systems, we have engines connected to alternators, which then connect to static inverters. The auxiliary power system runs off the static inverters, initially at 415V AC but distributed throughout the railcars at...
  43. Alexanddros81

    Determine stopping distance of a train - modified Euler method

    Homework Statement 12.81[/B] A train traveling at 20m/s is brought to an emergency stop. During braking, the acceleration is a=-(7/4)+(t/16) m/s^2, where t is the time in seconds measured from when the brakes were applied. (a) Integrate the acceleration from t=0 to t=16s using Euler's method...
  44. G

    A train sits on top of a 1% grade incline

    Homework Statement A train sits on top of a 1% grade. It accelerates uniformly until it reaches level track. What is the velocity the the train reaches on the incline, and how far does it travel before it comes to a stop? There is a 50 N braking force applied. Homework EquationsThe Attempt at...
  45. Alexanddros81

    Determine stopping distance of a train traveling at 20m/s

    This is problem 12.81 from Pytels Dynamics 2nd edition 1. Homework Statement A train traveling at 20m/s is brought to an emergency stop. During braking, the acceleration is a=-(7/4)+(t/16) m/s^2, where t is the time in seconds measured from when the brakes were applied. (a) Integrate the...
  46. jtbell

    Explore the Mystery of NYC's H Train

    Even if you're not a New Yorker, you probably know about the A train. And if you're a New Yorker or have visited New York, you may also know about the B, C, D, E, F, G, J, L, M, N, Q, R, S, V, W and Z trains. But you never hear about the H train. Have you ever wondered where it goes...
  47. R

    Why does the Japanese Maglev train use superconducting magnets

    My little home made air-core solenoid makes 1.5T, why is it that superconducting electromagnets often aren't stronger than one would expect. Take the japanese maglev train for example: http://www.supraconductivite.fr/en/index.php?p=applications-trains-maglev-more According to this article the...
  48. B

    Conservation of Angular Momentum of Train on Disk

    Homework Statement A horizontal plywood disk with mass 6.90 kg and diameter 1.14 m pivots on frictionless bearings about a vertical axis through its center. You attach a circular model-railroad track of negligible mass and average diameter 1.04 m to the disk. A 1.40 −kg , battery-driven model...
  49. DaveC426913

    German Electric Train Starts Singing: Is It True?

    This is adorable*. Is it true? http://digg.com/video/german-electric-train-start-music *if an electric train inadvertently does this as it's powering up
  50. G

    Doppler Effect: Velocity of a train

    Homework Statement To determine the speed of a train, a student of Physics determined the frequency of the whistle in the approach to its position of observation, and measured 220 Hz. He then determined the frequency of the whistle when the train moved away, and got 190 Hz. What is the speed of...
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