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Homework Help: Physics- vectors

  1. Sep 26, 2011 #1
    1. The problem statement, all variables and given/known data
    A child, sitting in the backseat of a car travelling at 20 m/s, throws a ball at 2 m/s to her brother who is siting in the front seat.
    a. what is the velocity of the ball relative to the children?
    b. what is the velocity of the ball relative to the road?

    V of car = 20m/s
    V of ball = 2 m/s

    2. Relevant equations

    Adding or subtracting?

    3. The attempt at a solution
    a. 20 m/s + 2m/s = 22 m/s
    b. 20 m/s + 2m/s = 22 m/s

    I am really confused
  2. jcsd
  3. Sep 27, 2011 #2
    When the problem states "relative to", it means pretending that the object, say the children or the road, is not moving. All the motion in the problem is based on everything else "moving" relative to the object you are using as your reference.

    Does this make sense?
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