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Math Help - speed and velocity

  1. #1
    Member jacs's Avatar
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    speed and velocity

    A particle moves along a straight line so that its displacement x metres from a fixed point O is given by x = t^3 - 6t^2 + 9t + 5, where t is measured in seconds.

    What is the average velocity of the particle over the first 3 seconds?

    What is the average speed of the particle over the first 3 seconds?



    I got the average speed to be 8/3 m's (which i hope is correct) but not sure what to do about the velocity.


    thanks
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by jacs View Post
    A particle moves along a straight line so that its displacement x metres from a fixed point O is given by x = t^3 - 6t^2 + 9t + 5, where t is measured in seconds.

    What is the average velocity of the particle over the first 3 seconds?

    What is the average speed of the particle over the first 3 seconds?



    I got the average speed to be 8/3 m's (which i hope is correct) but not sure what to do about the velocity.


    thanks
    The average velocity between t_1 and t_2 is:

    v_average = [x(t_2) - x(t_1)] / [t_2 - t_1]

    You are given the expression for x in terms of t, so you should now be able
    to find the average velocity.

    RonL
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  3. #3
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by jacs View Post
    A particle moves along a straight line so that its displacement x metres from a fixed point O is given by x = t^3 - 6t^2 + 9t + 5, where t is measured in seconds.

    What is the average velocity of the particle over the first 3 seconds?

    What is the average speed of the particle over the first 3 seconds?



    I got the average speed to be 8/3 m's (which i hope is correct) but not sure what to do about the velocity.


    thanks
    I just thought I'd add that your average speed is correct.

    -Dan
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