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Simple Questions, but confusing.

  1. Oct 17, 2003 #1
    Any help is appreciated!

    1)A man standing on a railroad flatcar moving at 1000ft/s to the left fires a bullet, whose muzzle velocity is 1000 ft/s in the opposite direction. What does an observer on the ground see teh bullet do?

    *I think he sees the bullet fire away at 2000 ft/s in the opposite direction

    2) A zoologist fires a tranquilizing dart directly at a monkey in a tree. At that very instant the monkey lets go and falls. Will the dart hit the monkey?

    *I yes because the dart will hit the monkey when they hit the ground.


    Thanks
     
    Last edited: Oct 17, 2003
  2. jcsd
  3. Oct 17, 2003 #2
    Let's do one at a time.

    Think about the situation BEFORE the gun fires. If the train is moving WEST at 1000 ft/sec. relative to the ground what is the speed and direction of the rifle relative to the ground ?
    What is the speed and direction of the bullet relative to the ground ?

    Now, the rifle fires. The bullet leaves the rifle heading EAST at 1000 ft/sec relative to the muzzle.

    What is the bullet's speed and direction relative to the ground ?
     
  4. Oct 17, 2003 #3
    Next question:

    When the monkey lets go, what happens to him? What is the direction and rate of his acceleration?

    When the dart leaves the muzzle, what is the direction and rate of its acceleration (not its velocity)?

    Now would you like to reconsider your answer?
     
  5. Oct 17, 2003 #4
    Hey, sorry for the late reply I had a english class.

    1) I believe that the speed relative to the ground will be 0 ft/s because 1000 ft/s West and 1000 ft/s east would cancel each other out. So the perso on the ground would see the bullet not moveing?

    2) The answer is yes, it will hit the monkey, Both the monkey and the bullet fall at -9.8m/s^2.

    Thanks, please let me know if i messed up...again.
     
  6. Oct 17, 2003 #5
    #1:
    So the person on the ground will see the bullet suspended motionless in the air?






    (Hint: see your answer to #2)
     
  7. Oct 17, 2003 #6
    haha, ok, let me try again. I think he will see the bullet move twice as fast away from the train.
     
  8. Oct 17, 2003 #7
    No, your previous answer (not moving) was closer to the truth. Almost, but not quite right.

    (What happens to the monkey and the dart?)
     
  9. Oct 17, 2003 #8
    They hit the ground at the same time.
     
  10. Oct 17, 2003 #9
    Right, but that's not what I'm talking about now. They don't hang suspended in the air, right?
     
  11. Oct 17, 2003 #10
    The observer is going to see the bullet drop!
     
  12. Oct 17, 2003 #11
    Eureka!

    I think you've got it.
    :smile:
     
  13. Oct 17, 2003 #12
    Thanks agian for all the help!!!
     
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