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    I understand that velocity is speed in a given direction and it is the measures the rate of change of displacement but i don't get the following:
    if a runner is completing one lap of a race at steady speed his avreage velocity is 0 and final displacement is 0
    a racing car in a race average velocity is 0 and final displacement is 0?
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    Average Velocity 0? Displacement I know would be 0 since he's right back where he started.. You've confused me.. maybe I'm just dumb.
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    as velocity is related to direction, imagine the runner is going around a circle. he travels in every direction, at every bearing, just once. and opposite directions will cancel each other out, making the total, and in turn the average, velocity as zero....
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    Half the race he runs away from his starting position, the other half he runs towards it. So average velocity is zero.
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    Imagine a very simple track, in which the runner runs one length and then turns around and runs back. the velocity on the way there is v m/s, and on the way back the velocity is -v m/s, as the direction is the opposite way, so the velocity is negative. So v and -v cancel out to leave average velocity 0
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    thank you every1 i think i get it now x
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    (Original post by panjabiflower)
    thank you every1 i think i get it now x
    :yy:
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    btw i hv this question saying 'how is it that an object moving in a circular path at constant speed does not have constant velocity' do i just explain how the average velocity will be 0 and explain how the opp directions cancel each other out?
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    (Original post by panjabiflower)
    btw i hv this question saying 'how is it that an object moving in a circular path at constant speed does not have constant velocity' do i just explain how the average velocity will be 0 and explain how the opp directions cancel each other out?
    As the object is moving in a circle, its direction of motion, and hence its velocity, is constantly changing, even though its speed remains constant
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    (Original post by sonofdot)
    As the object is moving in a circle, its direction of motion, and hence its velocity, is constantly changing, even though its speed remains constant
    so is its average velocity 0?
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    (Original post by panjabiflower)
    so is its average velocity 0?
    yes, but that alone wouldn't answer the original question of why the velocity changes even though the speed is constant
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    At any one point, the velocity will not be zero (unless at that point the runner stops or changes direction). Average velocity is only zero within a given time interval if you have zero displacement after the time interval, even if during your velocity was changing. So the average velocity of the runner AFTER completing a lap is zero. At any other time during it would not be zero.
 
 
 
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