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Homework Help: 2 challenge problems for tommorrow(dec 7)

  1. Dec 6, 2004 #1
    Second one:
    Protons are projected at an angle of 300 with an initial speed, given by V0=8.2*105 m/s, in a region of an electric field E=-390j N/C, is present. The proton is to hit a point 1.27 mm in the pos-x direction from the launch point. Find (a) the two porjections angles (theta) that will result in a hit, and (b) the total time of flight for each of these two trajectories.

    Here is what I can get for this one.
    (theta)=cos-1(V0x/V0)
    (theta)=sin-1(V0y/V0)
    F=q*E=-1.15*10-16 N
    a=F/m=-6.89*1010 m/s2


    First one: Solved
    on an analogue clock the minute hand aligns perfectly with the hour hand once and hour. 12:00 is the first time, when are the exact other times this happens. (Hint: in only happens 11 times, not 12 and the hour and minute hand constantly move)

    time=3927.272727s*n
    where n is the number of times the min hand has ligned up with the hour hand
    ex:
    1st time...........1:05:27.2727
     
    Last edited: Dec 6, 2004
  2. jcsd
  3. Dec 6, 2004 #2

    Tide

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    Homework Helper

    re: the first one

    The hands will coincide every [itex]\frac {12}{11}[/itex] hours. Just convert that to hours, minutes and seconds.
     
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