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Homework Help: True or False ^^pls correct me if im wrong

  1. Jul 27, 2007 #1
    Hihihi it takes only general knowledge ^^ pls correct me if I'm wrong pls :)

    1) Three dimensions are necessary to describe the general motion of a particle. (False) it can be done with one dimension analysis...

    2) A component of a vector is itself a vector (false) component is a scalar quantity right?

    3) All vector quantities have both a magnitude and a direction, and all follow the same rules for vector addition and consecutive displacements follow. (True) can't explain but i believe so....

    4) The magnitude of a vector is a dimensionless number (false)

    5) vectors may be added by adding corresponding components (no idea ^^)

    6) for any two vectors P and Q, P - Q is a vector having the same magnitude as, but a direction opposite to P + Q (true) vectors will have the same magnitude but a different direction.

    7) the instantaneous velocity vector is always in the direction of motion (pls explain further ^^)

    8) If a particle moves in a straight line, its position and velocity vectors are parallel (false????? wouldn't it intersect pls help)

    9) a projectile is a body in motion that cannot be treated as a particle(false because it is a particle at all certain points in the projectile motion)

    10) an object can be treated as a particle if both its rotational motion and its internal structure do not vary ( sorry i don't understand)

    other questions answer if you can ^^

    1)you throw a baseball from the outfield to a friend at home plate. in general, the distance the ball travels is not equal to the magnitude of its displacement vector. which of the two is larger?

    2)Is the relation between velocity and position identical to the relation between acceleration and velocity?

    3)An elevator is moving up at a speed v when a bolt falls from its undercarriage. what actually happens to the bolt?

    HAVE FUN :)
  2. jcsd
  3. Jul 27, 2007 #2
    it seems you dont have a good idea of vectors. first try to brush up your concepts about vectors, you ll get the explanations

    now your other 3 questions
    do you know the difference b/w distance and displacement??? anyways distance is larger(try figuring that out by thinking about the definition of two)
    yes the relation is same, vel is the rate of change of position, and acceleration is the rate of change of velocity
    bolt falls off, what else. but it takes a lil longer to drop to the ground. remember the bolt has an upward velocity
    Last edited: Jul 27, 2007
  4. Jul 27, 2007 #3


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    Staff: Mentor

    What class are you taking? What equations are introduced in the chapter that this question is from? As ank_gl says, you need to re-read the chapter on vectors a bit more, and then try answering the questions again. And please include your reasoning with the answers -- otherwise you are just guessing.
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