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Homework Help: Newton's third law of motion help

  1. Jul 23, 2011 #1
    Hello!! My question is about Newton's 3rd law:

    Which one of the following is true, according to Newton's laws of motion? Ignore friction.

    a. an SUV hits a stationary motorcycle. Since it is stationary, the motorcycle sustains a greater force than the SUV does
    b. a semitrailer truck crashes all the way through a wall. since the wall collapses, the wall sustains a greater force than the truck does.
    c. sam (18 years old) and his sister (9 years old) go ice skating. they push off against each other and fly apart. sam flies off with greater acceleration.
    d. two astronauts on a space walk are throwing a ball back and forth ebtween each other. in this game of catch the distance ebtween them remains constant
    e. none of the above is true, according to the third law.

    I know that the answer is E, that none of the above is true, but I do not understand what D is saying. How does E apply to the third law?

    Thank you so much in advance!! :)
  2. jcsd
  3. Jul 23, 2011 #2
    Ohhh okay I think I may have gotten it. Is it because as you throw a ball, you exert a force on the ball, in the direction of the catcher. Thus, there's an equal and opposite force placed upon you (the thrower). So you are propelled further and further from the other person (the catcher)?
  4. Jul 23, 2011 #3
    In throwing and catching the ball, you exert a force on the ball. Because of the opposite force from the ball, the distance will increase (not because of a force between the catcher and thrower)
  5. Jul 23, 2011 #4
    Thank you!!!! :)))
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