RELATIVE MOTION wooden boxcar, sniper, bullets oh my

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SUMMARY

The discussion centers on a physics problem involving relative motion, where a wooden boxcar moves at 85 km/h while a sniper fires a bullet at 650 m/s. The bullet's speed decreases by 20% upon entering the boxcar, leading to a need for analysis using the Pythagorean theorem to determine the angle of the bullet's trajectory relative to the track. The problem requires understanding the relationship between the bullet's speed, the boxcar's speed, and the geometry of the situation, particularly how to set up the triangle for calculations.

PREREQUISITES
  • Understanding of relative motion concepts
  • Knowledge of the Pythagorean theorem
  • Familiarity with basic kinematics
  • Ability to analyze vector components
NEXT STEPS
  • Study the principles of relative velocity in physics
  • Learn how to apply the Pythagorean theorem in motion problems
  • Explore vector decomposition techniques
  • Review the effects of speed changes on projectile motion
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and relative motion, as well as educators seeking to clarify complex concepts in kinematics.

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Homework Statement



A wooden boxcar is moving along a straight railroad track at speed v1. A sniper fires a bullet (initial speed v2) at it from a high powered rifle. The bullet passes thought both lengthwise walls of the car, its entrance and exit holes being exactly opposite each other as viewed from within the car. From what direction, relative to the track, is the bullet fired from? Assume that the bullet is not deflected upon entering the car, but that its speed is decreased by 20%. Take v1 to be 85 km/h and v2 = 650 m/s.

Homework Equations



3eca9149-c5a9-457f-ab77-365aa4d7a3d5.jpe


The Attempt at a Solution



I don't understand what is going on. Can someone please explain the explanation to me. For example, why is the triangle set up as it is. Why is the hypotenuse the speed of the bullet as it is leaving the boxcar? And why do we have to subtract from 180 degrees.
 
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I understand that the bullet is fired from an angle that is perpendicular to the track, but I don't understand why we have to use the Pythagorean theorem and why we are subtracting from 180 degrees. Can someone please explain this to me. Thanks!
 

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