Kinematics Problem: Train braking and blocking an intersection

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SUMMARY

The discussion centers on a kinematics problem involving a train that is 400 meters long, initially traveling at a speed of 21.6 m/s. After applying brakes, the last car of the train passes a crossing at a speed of 5.0 m/s. The objective is to determine the duration for which the train blocks the crossing, assuming constant acceleration. The incorrect solution provided was 37.04 seconds, indicating a need for proper application of kinematic equations to find the correct time.

PREREQUISITES
  • Understanding of kinematic equations, specifically the "big four" equations.
  • Knowledge of constant acceleration concepts in physics.
  • Ability to manipulate equations to solve for time, velocity, and acceleration.
  • Familiarity with basic algebra for solving equations.
NEXT STEPS
  • Review the kinematic equation: \( v_f = v_i + at \) to determine acceleration.
  • Learn how to apply the equation \( d = v_i t + \frac{1}{2} a t^2 \) for distance calculations.
  • Practice solving similar kinematics problems involving braking scenarios.
  • Explore graphical representations of motion to visualize acceleration and deceleration.
USEFUL FOR

This discussion is beneficial for physics students, educators teaching kinematics, and anyone interested in solving real-world motion problems involving trains and braking dynamics.

Zacharrry
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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. Disregard the width of the crossing.

Homework Equations


One of the "big four" kinematics equations (velocity, initial velocity, time, acceleration, etc.)

The Attempt at a Solution


I tried the problem and got 37.04 seconds, but it told me it was incorrect. I am not sure what I did wrong, so can anyone help by telling me what they got and/or how to solve it?
 
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You need to show what you did, which of the big four formulae you used, what numbers you put in, etc.
 
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