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. M

    The Doppler Effect: A Train Approaching a Stationary Observer

    A train (source) approaching a stationery observer, wavelength of the sound is equal to the distance between source and observer, How?
  2. E

    Train Collision Problem - Calculating Head Start

    Homework Statement The engineer of a passenger train traveling at 25.0 m/s sights a freight train whose caboose is 200 m ahead on the same track. The freight train is traveling at 15.0 m/s in the same direction as the passenger train. The engineer of the passenger train immediately applies...
  3. P

    Confusion with train collision with constant acceleration

    The problem statement A train starts out from Stavanger at 8.14, in direction of Kristiansand. It goes with constant speed, 80.0km/h until Sandnes, a distance of 15.0 km. Then it accelerates (instantaneously) to 120 km/h and proceeds towards Kristiansand. Kristiansand is 250 km from...
  4. J

    Train thought experiment confusion

    I'm seeing examples where for the person in the train the offset of both lights at the end of the train are not seen as simultaneous, while for the observer on the platform it is seen as simultaneous - and vice versa from other sources. What's going on? Furthermore, if my school textbook is...
  5. H

    Questions on length contraction in train light clock experiment?

    Hi guys, I've been thinking about this experiment for the last few hours and I have a few questions which I am deeply confused about. 1) In the light clock experiment, where light clock is set up so that light travels vertically, and the train carrying the clock travels horizontally, wouldn't...
  6. lisab

    Look at one point - can you make the train change directions?

    When I look at the top of the gif, the train comes toward me. When I look at the bottom, it goes away from me. I have a hard time making it change while looking at the same spot, though.
  7. T

    Imparting Linear Momentum: Examining a Train Car Example

    This is not a problem, it is just a concept check :shy: What does it mean that something does not impart linear momentum to the rest of the system? For example grain leaking out a train car.
  8. S

    Train Kinematics Problem

    Homework Statement Two trains, one traveling 60.0mph east and the other traveling 90.0mph west, are on the same track. When they are 10000 ft apart both train's brakes are applied. If they both have the same deceleration, what is the minimum deceleration to prevent a collision? Homework...
  9. C

    Faraday's paradox: homopolar generator on a train

    There is a homopolar generator on a train moving at 215 km/h. The magnet of the generator is attached to the disk so they would rotate together, but they are stationary now, except that they are moving along with the train. Is there any current generated by the generator? I expect the answer...
  10. C

    How Do You Calculate the Young's Modulus of Spiderman's Webs from Spiderman 2?

    Hi, we've recently been set a task by our physics teacher to try and calculate the Young's Modulus of Spiderman's webs in the train stopping scene of Spiderman 2. Doing research on the mass of the carriage + passengers, calculating forces from that and also using things like the velocity...
  11. A

    Running & Jumping Backwards on a Moving Train

    Hello. I've searched a lot on the internett on jumping inside a train, and I do only find solutions for the question "When u jump inside a train will u land at the same spot, whereas the train is moving u should land bit back". What happens if you are running and jumping backwards, would you...
  12. Govind_Balaji

    Velocity of train if it passes 2km bridge in 110sec and a point in 10s

    Homework Statement A train passes through an electric post in 10 seconds. With same velocity, it passes through a 2km long bridge in 110 seconds.Find the velocity of the train: a)18kmph b)36kmph c)72kmph d)90kmph. Homework Equations The Attempt at a Solution...
  13. P

    Special relativity theory train and mosquito

    Homework Statement Train is moving along the x-axis with speed v relative to platform, inside the train mosquito is flying with 3D speed v0. 1) Write mosquito s 4-speed components with respect to train coordinate system. 2) Using 4-vector component transformation write mosquito's 4-speed...
  14. A

    Train Stopping Time: Different Observers, Different Times?

    Lets have a train moving to the right side in the shown direction of the arrow. From a point near the end A, 2 rays of light are emitted toward both ends A and B so as they appear to reach both ends at the same time for an external observer. At the moment the 2 rays reaches the 2 ends at the...
  15. C

    How large is the greatest slope this train can climb?

    Homework Statement A train wheel's have a coefficient of 0.08. What is the steepest slope the train can climb? Homework Equations Friction force = coefficient x component of train's weight perpendicular to slope x 9.81 If the train is on the point of slipping Friction force =...
  16. M

    Train Velocity: Calculating Midpoint Velocity at Instant

    1. If a train engine is traveling with initial velocity 'u' and the guard's coach(last coach of the train) is found to cross a pole with velocity 'v', then what is the velocity of the midpoint of the train at that instant?
  17. A

    Time Question - how long did the train block the crossing?

    Time Question -- how long did the train block the crossing? Homework Statement A commuter train 500 m long travels on a straight track at a speed of 78.6 km/h it slows down as it approaches a crossing. The last car passes the crossing at a speed of 15.8 km/h. With a constant acceleration, how...
  18. Adithyan

    Speed of sound on a moving train

    Homework Statement Two trains A and B are moving with speed 20m/s and 30m/s respectively in the same direction on the same straight track with B ahead of A. The engines are at the front ends. The engine of trains A blows a long whistle. Assume that the speed of sound of whistle is...
  19. X

    Why Are T1 and TL Negative in Gear Train Dynamics?

    Homework Statement See attachment. Homework Equations The Attempt at a Solution Equations (1) and (2) describe this gear train system. I'm confused about them. For (1): If I rewrite it (∑F=0 format) I get: T-T1-Jθ''-Bθ' = 0 The figure clearly shows θ1 positive spinning...
  20. ecoo

    Einstein's Train Thought Experiment

    I recently watched a video in Einstein's train though experiment. www.youtube.com/watch?v=wteiuxyqtoM From what I got from it, events can appear to be at different times when compared to each other depending on the observer. But isn't there an absolute event timing of when the events...
  21. J

    How do I find the speed of this train?

    Homework Statement Two train whistles have an identical frequency of 246 Hz. Train A is motionless in the station and sounds its whistle. Meanwhile, Train B is pulling into the station and sounds its whistle. The conductor of Train B hears 5.39 beats every second. How fast is Train B moving...
  22. Y

    4-acceleration of a vector in a linearly moving train

    Consider the thought experiment in the diagram below. According to the authors, the vector will rotate even in the rest frame of the moving train relative to the body of the train. Is it possible to consider the spin axis of the gyroscope represented by the vector as a simple rod and...
  23. E

    Train Motion Homework: Review Criteria & Find Solution

    Homework Statement You are an engineer working for a new interstate bullet train start-up company. Your manager, Saul Enderman, is charged with designing the first 1500-meter-long segment of a new train line. (Another team is in charge of designing the remaining segments of the line.) During...
  24. I

    Find the tension between two train carts as the train brakes.

    This was from my last exam. I got this problem wrong. I feel like I should have known how to do it but I blanked out or something. Just coming here to figure out how it's supposed to be done. (This is from what I remember, numbers may be off from what was on the test) I know I got it wrong...
  25. J

    Does Relativistic Motion Affect Time Perception on Moving Trains and Platforms?

    Here is another train and platform example, offered to examine ghwellsjr's view equating what you see with what is real. Assumptions: Train has proper length 100. Platform has proper length 60. Train and platform are in relative inertial motion at 0.8c. There are two observers on the...
  26. I

    Question about Einstein's train thought experiment

    Hi all. I'm a run-of-the-mill layman—not a student. I've just developed an interest in physics lately and have been watching/reading a lot pop physics. So hopefully my question's not too stupid and hopefully the answer's not too far over my head. My question is about the thought experiment...
  27. M

    Archived Special relativity: train between two cities

    Homework Statement A high-speed train is traveling from Capital City to Shelbyville. According to an observer at rest on the ground, the clocks at the railroad stations in Capital City and Shelbyville both strike noon at the same time. According to a passenger on the train, when the Capital...
  28. C

    Special Relativity, Train, Ball

    Homework Statement A train with proper length L moves at speed 5c/13 with respect to the ground. A ball is thrown from the back of the train to the front. The speed of the ball with respect to the train is c/3. As viewed by someone on the ground, how much time does the ball spend in the air...
  29. L

    Calculating Gear Ratio for Epicyclic Gear Train

    Homework Statement Here the gear B is fixed and C and D are on the same drive. If C has 100 teeth, B has 50, D has 50 and E has 200. Calculate the ratio of the gearbox. Homework Equations The Attempt at a Solution My attempt is uploaded as an attachment as putting tables in...
  30. bcrowell

    Reading on a scale inside a train

    I recently came across this paper http://arxiv.org/abs/physics/0504110v2 by Oas that is a semi-rant about how pedagogically evil relativistic mass is. He gives the following sample question: From the context, it appears that the students are expected to have little or no background in...
  31. S

    Rephrasing the train and platform thought experiment

    Hi all, I'm sure that things similar to this have been covered before. Also, I'm sure that a Minkowski diagram would probably clear things up no end but, anyway, please bear with me. Let's assume that we have our familiar railway carriage packed with observers who are satisfied that they...
  32. O

    Final velocity and total mass of train car below hopper

    Homework Statement A cart, starting at rest, is below a hopper at t=0. The hopper drops coal into the cart at a constant rate μ. At t=0 a constant force starts pushing the cart to the right and the coal begins to fall. The force ends once the back of the cart passes the hopper. A) Find...
  33. P

    Multiple coil field math for magnetic train

    i need to know how to calculate the inductance and field strength of a coil while another coil directly beneath it is turning off and coils under that are also turning off i also need to know how quickly the coils will turn off and if i can accelerate the process if it makes a difference the...
  34. O

    How Far From the First Station Do Two Oppositely Accelerating Trains Meet?

    Homework Statement Two trains start from rest from two stations 5.0 km apart and travel, on two parallel railroad tracks, in opposite directions. One train accelerates uniformly at 2.5 m/s^2 and the other has a constant acceleration of 4.0 m/s^2. How far from the first station will they...
  35. W

    Similar to the Einstein train experiment

    Please help with this. This is similar to the Einstein train experiment. When C and C' are at the same place, lightning strikes at their location. Both survive though. Assume another prime B' behind C' When B' is at the same location as C, the lightning is at (A,0,0) and (-A,0,0) in the C...
  36. N

    Einstein's train thought experiment

    https://scontent-a-ams.xx.fbcdn.net/hphotos-prn1/601539_10201811069735094_388925769_n.jpg Why did they define the lightning event to be simultaneous for Stanley? Why can't it be simultaneous for Mavis, so that the lighting hits A first?
  37. L

    How Does Wind Affect the Doppler Effect in a Two-Train Scenario?

    Homework Statement Two trains are traveling toward each other at 30.0 m/s relative to the ground. One train is blowing a whistle at 480 Hz. (a)What frequency is heard on the other train if the wind is blowing at 30.0 m/s toward the whistle and away from the listener? (assume the speed of sound...
  38. G

    A car and a train colliding with each other.

    Homework Statement A car and a train collides with each other in an elastic collision. The mass of the train is much more larger than the mass of the car. Ignore air resistance and friction from the railway tracks and roads. Just before impact the car has a velocity of (V) train has a velocity...
  39. H

    The horizontal distance the train will move before its speed reduces?

    Homework Statement A 60,000 kg train is being pulled up a 1% gradient by an engine exerting 3 kN. The frictional force opposing the motion of the train is 4 kN. The train’s initial speed is 12 m/s. Through what horizontal distance will the train move before it’s speed is reduced to 9 m/s...
  40. L

    Gear train torque / power and load?

    Homework Statement This is a final hurdle of a long question designing a simple gear train. That is done but now am not sure of my calculations for power in / out and torque in and out, so hopefully someone can help? OK - I have 4 spur gears inline, Gear A = 100 rpm 80 Teeth (input motor...
  41. Crazymechanic

    Can electric trains charge capacitors with only a positive supply wire?

    Hi , I observed an older type of electric train yesterday which is a DC train having a +ve overhead wire with around 3000v in it. Now as I was sitting there I saw the capacitor banks below the train , probably used to smooth the incoming voltage for peaks and stuff to feed that further to the...
  42. stateofdogma

    Solving a Tricky Tension Problem on a Moving Train

    Homework Statement A bored but observant child on a moving train ties a ball to one end of a string and ties the other end to a light fixture on the ceiling of the train. When the train slows down, the child notices that the string is no longer hanging straight down but instead makes an angle...
  43. M

    Double slit experiment on a moving train

    So I asked this question in another thread but thought the question was probably best asked here in this forum to at least understand part of the experiment. My idea follows the traditional train and platform analogy that is used in many thought experiments to explain the issue of simultaneity...
  44. O

    Find V(t) of train car with changing mass.

    Homework Statement An empty freight car of mass M starts moving from rest with a constant applied force F0. At the same time, coal runs into the car at steady rate b from a hopper above the car at rest along the track. Calculate the velocity of the car as a function of time. Data: M = 1900...
  45. S

    Special Relativity: Bullets on a train

    Homework Statement A train moves at speed v. Bullets are successively fired at speed u (relative to the train) from the back of the train to the front. A new bullet is fired at the instant (as measured in the train frame) the previous bullet hits the front. In the frame of the ground, what...
  46. R

    Solving the Train Length Ratio Puzzle

    Homework Statement Two trains, A and B, are moving towards each other with relative speed 0.8c. The passing of the two trains (from when their fronts align to when their backs align) takes 20% longer as observed from train A as is does as observed from train B. What is the ratio of the length...
  47. A

    Square Pulse Train Fourier Series help?

    Square Pulse Train Fourier Series help?? Homework Statement problem+directions below: Homework Equations ω=2\pif β=\frac{2\pi}{\lambda} The Attempt at a Solution Since the problem asks to make all time-dependent sinusoidal functions deal with x-direction, i don't think i need to...
  48. M

    Need to compute distance during during acceleration of a train

    Homework Statement A train is traveling down a straight track at 20 m/s when the engineer applies the brakes, resulting in an acceleration of -1.0 m/s2 as long as the train is in motion. How far does the train move in a 40-s time interval starting at the instant the brakes are applied...
  49. D

    Electromagnetism: Axle rolling on train rails

    Imagine a set of train tracks. Now there is one bridge (a resistor) connecting the two rails in one spot. On a different spot, there is rolling axle that acts as another bridge and it makes good electrical connection with the rails creating a full rectangular circuit. This axle rolls at a...
  50. A

    Why did the crude oil train crash and explode in Canada?

    Could someone please explain how crude oil could explode as shown in the recent crash in Canada. see: http://www.stuff.co.nz/world/americas/8943438/Insufficient-brakes-led-to-runaway-train
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