Qualification > Sciences

question on physics...have a doubt...

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Tyserius:
Average speed = Total distance travelled / Total time taken

So without the time / distance, you can't solve it =/

falafail:
ohhh, okay. i get it.

let's assume the distance from A to B is d, so the total distance is 2d.
then, using d=st, you find that the time from A to B is d/40 and from B to A is d/120
so the total time = d/40 + d/120
and the average speed = 2d / (d/40 + d/120)
= 2d / (3d/120 + d/120)
= (2d x 120) / 4d
= 240d / 4d
= 60

;D

Tyserius:

--- Quote from: falafail on November 10, 2009, 05:40:12 pm ---ohhh, okay. i get it.

let's assume the distance from A to B is d, so the total distance is 2d.
then, using d=st, you find that the time from A to B is d/40 and from B to A is d/120
so the total time = d/40 + d/120
and the average speed = 2d / (d/40 + d/120)
= 2d / (3d/120 + d/120)
= (2d x 120) / 4d
= 240d / 4d
= 60

;D

--- End quote ---

Oh hahahaha! I forgot about the unknowns. Crap, Econs is lagging me behind for Physics T_T

helllife:
oh....i got it!!! genius!!!! ;) ;)
Thanx ...will post question more later!! ;D

falafail:

--- Quote from: helllife on November 10, 2009, 05:53:44 pm ---oh....i got it!!! genius!!!! ;) ;)
Thanx anyways...will post question more later!! ;D

--- End quote ---

hah, well i'll try my best to help :)



--- Quote from: Tyserius on November 10, 2009, 05:41:39 pm ---Oh hahahaha! I forgot about the unknowns. Crap, Econs is lagging me behind for Physics T_T

--- End quote ---

oh noes D:

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