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-   -   Free fall (https://www.askmehelpdesk.com/showthread.php?t=59267)

  • Feb 1, 2007, 11:03 AM
    tnhoots
    Free fall
    1.A hawk is flying horizontally at 11.0 m/s in a straight line, 220 m above the ground. A mouse it has been carrying struggles free from its grasp. The hawk continues on its path at the same speed for 2.00 s before attempting to retrieve its prey. To accomplish the retrieval, it dives in a straight line at constant speed and recaptures the mouse 3.00 m above the ground.
    (a) Assuming no air resistance, find the diving speed of the hawk.
    (m/s)
    (b) What angle did the hawk make with the horizontal during its descent?
    (° below the horizontal)
    (c) For how long did the mouse "enjoy" free fall?
    (s)

    I am completely lost. Physics and I don't get along very well, as I'm sure you all have noticed from all my numerous posts. A push in the right direction would be great..?

    PLEASE HELP! This is a review question from an exam that I have coming up... and I am completely lost. Any assistance would be greatly appreciated!!
  • Feb 2, 2007, 12:49 AM
    Capuchin
    We need to look at the horizontal and vertical components separately, as you can often do in physical systems (this is because the vertical direction has gravity applied, whereas the horizontal direction doesnt).

    assuming no air resistance, we can assume that the mouse will always be travelling horizontally at 11 m/s, since the hawk is always travelling at 11 m/s also, they hawk, in order to catch the mouse will have to be moving 11 m/s horizontally.

    I'll answer by outlining the steps you must take

    a)
    Using suvat equations:
    for this part, assume there is no horizontal movement until the end, we've already dealt with it
    How long does it take for the mouse to fall to 3m? (you aren't given gravity but I think you can assume 9.8m/s)
    How fast must the hawk dive to reach 3m at the same time as the mouse (remember the mouse has a 2s head start) (you can use v=d/t)
    Using 11m/s for the horizontal speed of the hawk, and the speed you just calculated as the vertical speed, you can use Pythagoras' theorem to work out the total speed.

    b)
    Using trigonometry, you can work out the angle of the dive.

    c)
    You've already answered this in a) using suvat equations.

    If you need any further help understanding any of the above, or want me to check your answer, please feel free to ask.

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