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Homework Help: Displacement and direction

  1. Feb 11, 2008 #1
    Out of 20 review questions, I stuck on this three, please help.

    A scout troop is practicing its orienting skills with map and compass. First they walk due east for 1.1 km. Next, they walk 45° west of north for 2.1 km. In what direction must they walk to go directly back to their starting point? How far will they have to walk?

    Ok for what I did: a: x=1.1, y=0; b:-1.5, 1.5 (using sin(45)=O/2.1) a+b= squareroot of 0.4^2 + 1.5^2 = 1.6 That's how far they have to walk.

    Angle = sin^-1=1.1/2.1 = 32degree southeast.

    What did I do wrong?

    Q2. At t = 0, an automobile traveling north begins to make a turn. It follows one-quarter of the arc of a circle of radius 15.0 m until, at t = 1.6 s, it is traveling east. The car does not alter its speed during the turn. Find (a) the car's speed, (b) the change in its velocity during the turn, and (c) its average acceleration during the turn.

    a: 1/4*2*pi*15 / 1.6s = 15m/s
    b: sqr(15^2+15^2) = 21 m/s southeast
    c: 0, because the speed didn't change so there was no acceleration.

    I also got that one wrong. What did I do wrong?

    3. A 2.30 kg toy locomotive is pulling a 1.60 kg caboose. The frictional force of the track on the caboose is 0.460 N backward along the track. If the train is accelerating forward at 2.50 m/s2, what is the magnitude of the force exerted by the locomotive on the caboose?
    This one I have no idea how to approach it.
    Last edited: Feb 11, 2008
  2. jcsd
  3. Feb 11, 2008 #2
    Can one help? Maybe just the first question is fine.
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