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# can any1 explain velocity to me? watch

1. 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?
2. 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.
3. 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....
4. Half the race he runs away from his starting position, the other half he runs towards it. So average velocity is zero.
5. 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
6. thank you every1 i think i get it now x
7. (Original post by panjabiflower)
thank you every1 i think i get it now x
8. 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?
9. (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
10. (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?
11. (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
12. 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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