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Homework Help: Displacement and vector problems

  1. Sep 24, 2010 #1
    Ok, so I am having a difficult time with vectors (despite the fact that it appears to be an easy concept). My main issue is I am so focused on my AP Calc and AP English classes that I have not had much time for any studying, so I rely on what I hear during the course. I am required to complete this assignment and it is worth 60% of my grade, and part of it is on Vectors. That being said, I am in need of help to understand this. If you do not feel like answering some of these, any advice would be greatly appreciated on HOW you would solve a question of that sort. I will provide all of the questions (or if there are multiple questions with same basic concept, I will just show 1) and all of my work up to where I get lost. Thanks in advance!

    1. A plane travels 2.0 km at an angle of 33◦ to the
    ground, then changes direction and travels 7.7
    km at an angle of 18◦ to the ground.
    What is the magnitude of the plane’s total
    displacement?
    Answer in units of km. At what angle above the horizontal is the
    plane’s total displacement?
    Answer in units of ◦


    -For this particular question, I am stuck. For some reason, I am not understanding how to do this....


    2. An airplane flying parallel to the ground un-
    dergoes two consecutive displacements. The
    first is 33 km at 18.3◦ west of north, and the
    second is 174 km at 65.5◦ east of north.
    What is the magnitude of the plane’s total
    displacement?
    Answer in units of km. At what angle east of north is the plane’s total
    displacement?
    Answer in units of ◦.


    -After calculating the side (hypotenuse) I got 158.33 but it was wrong

    3. A quarterback takes the ball from the line
    of scrimmage, runs backward for 15.0 yards,
    then runs sideways parallel to the line of
    scrimmage for 15.0 yards. At this point,
    he throws a 21.0-yard forward pass straight
    down the field.
    What is the magnitude of the football’s
    resultant displacement?
    Answer in units of yards.


    -Now this one I am lost on. I had this on a quiz a few days back and missed it. I set it up to where there is a triangle with one side being 6 (6 left over from the 21 yrd pass past the 15yrds where it started) and the other side being 15 (when making it a right triangle). Then I did a^2+b^2=c^2 and got 16.15. I believe that is right but I am afraid to answer before making sure.

    4. The eye of a hurricane passes over Grand
    Bahama Island. It is moving in a direction
    57.2◦ north of west with a speed of 34.6 km/h.
    Exactly 2.97 hours later, the course of the
    hurricane shifts due north, and its speed slows
    to 28.8 km/h, as shown.
    How far from Grand Bahama is the hurri-
    cane 4.23 h after it passes over the island?
    Answer in units of km.


    -Got really lost on this one. I would assume you would first subtrade 2.97 from 4.23, then times that by 28.8 to get the distance then find the hypotenuse?

    5. A submarine dives 185.0 m at an angle of
    13.0◦ below the horizontal.
    What is the horizontal component of the
    submarine’s displacement?
    Answer in units of m.What is the vertical component of the subma-
    rine’s displacement?
    Answer in units of m.
     
  2. jcsd
  3. Sep 24, 2010 #2
    Re: Vectors

    Update**
    .
    For #1 I think I found the solution. I made the triangle and split it into a right triangle and got 2tan36 which is 1.45 and the angle of it would be 72 degrees?

    Edit: My answer was wrong >.<..im clueless
     
    Last edited: Sep 24, 2010
  4. Sep 24, 2010 #3
    Re: Vectors

    Could really use help..this is due in 2 hours and I am completely stuck. I have already answered them all 3 times with different answers that are all wrong. I don't even mind if you won't give answer but some help on HOW to get answer would be MUCH appreciated!
     
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