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-   -   position time (http://physicshelpforum.com/kinematics-dynamics/4791-position-time.html)

 ohm Aug 16th 2010 09:31 AM

position time

can anyone give me two examples having velocity and displcement just in opposite direction( if vel is +ve then disp is -ve and vice versa)?
Thanks

 ChipB Aug 16th 2010 10:10 AM

I'll give you one example, then perhaps you can think of another on your own.

When you throw a ball into the air, after some period of time it reaches its maximum height and then starts to fall back to the ground. While it is falling, and before it hits the ground, the displacement of the ball is positive (it's above the ground) but its velocity is negatrive (it is falling).

I'm sure you can think of other example involving things like bouncing basketballs, or yo-yo's.

 ohm Aug 16th 2010 11:25 AM

suppose I take upward direction as +ve .
Now, i throw a ball verticaly upward with a vel v. It reaches at maximum height +s(disp +ve, velocity also +ve) then falls down by covering -s(disp -ve,vel also -ve). Thus total disp: +s-s=0. I think in ur case it should be 2s( so how is it possible?)

 ohm Aug 17th 2010 10:17 PM

can anyone comment?

 ohm Aug 18th 2010 06:31 AM