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Free Fall Help

  1. Sep 18, 2006 #1
    Hello everyone! I'm a senior in high school, new to the forums and need some help, mainly because I got a 59% on my first test :uhh:

    I am a physics newbie and need a lot of help :cry:
    For starters, I have a couple questions here that i would like help with.

    1)A photographer in a helicopter ascending vertically at a constant rate of 12.5m/s accidentally drops a camera out the window when the helicopter is 60m above the ground. (A) How long will it take the camera to hit the ground? (B) What will its speed when it hits?

    -Is the 12.5m/s INITIAL Velocity (V0) or regular Velocity (V)? My friend
    and I were debating over this all class and we couln't reach an agreement.

    2)A car and motorcycle start from rest at the same time on a straight track, but the motorcycle is 25.0m behind the car. The car accelerates at a uniform rate of 3.70m/s2 (meters per second squared), and the motorcycle at a uniform rate of 4.40m/s2. (A) How much time elapses before the motorcycle overtakes the car? (B) How far will each vehicle have traveled by that time? (C) How far ahead of the car will the motorcycle be 2.00seconds later?

    -Could someone lead me through these sample problems step by step? I know that you guys aren't here to do my homework, but I don't know where to begin. I'd like to eventually be able to do my homework without having to ask people for help all the time. :mad:

    Thank you very much!
    -Nick :biggrin:
  2. jcsd
  3. Sep 18, 2006 #2


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    Homework Helper

    Welcome to PF!

    Considering 1), 12.5 is, of course, the initial velocity. Considering both 1) and 2), look up some basic kinematic equations. Both questions are about motion with constant acceleration, so find the equations which describe such motion, think about them a bit, and apply them to your problems. I'm sure you'll find your way through quick! :wink:
  4. Sep 18, 2006 #3


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    Science Advisor
    Homework Helper

    The moment the man drops his camera it still has the upwards velocity of 12.5 m/s, so it's the initial velocity when it starts falling. It will, ofcourse accelerate towards the ground with acceleration g (or -g depending on your choice of axes).

    Well, I`m sure you know the formulas for position as a function of time given a constant acceleration, initial velocity and initial position.
    First thing to do is to choose a coordinate system, say you choose the position x=0 is where the motorcycle starts. Write down their positions as a function of time. From these euqations you can solve A,B and C. You just have to translate the word questions into the right corresponding mathematical question.
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