# Thread: PHYSICS---am i doing anything wrong?

1. ## PHYSICS---am i doing anything wrong?

Starting speed is 30 m/s
End speed is 15 m/s
Time elapsed is 3 s
Find the distance traveled (acceleration is constant)

the formula they gave me is

$\displaystyle x-x^0=1/2(v^0+v)t$

just pretend the $\displaystyle ^0$ is below not above, i dont know how to do sub-0 sorry.

anyway, i plug it all in and get

$\displaystyle 1/2*(15+30)*3=67.5 m$

But the book says the answer is 90 m

thanks to any1 who helps! i think the book may be wrong, it wouldn't be the first time, but I'd like to be sure.

2. Originally Posted by Chokfull
Starting speed is 30 m/s
End speed is 15 m/s
Time elapsed is 3 s
Find the distance traveled (acceleration is constant)

the formula they gave me is

$\displaystyle x-x^0=1/2(v^0+v)t$

just pretend the $\displaystyle ^0$ is below not above, i dont know how to do sub-0 sorry.

anyway, i plug it all in and get

$\displaystyle 1/2*(15+30)*3=67.5 m$

But the book says the answer is 90 m

thanks to any1 who helps! i think the book may be wrong, it wouldn't be the first time, but I'd like to be sure.
"am I doing anything wrong?" - yes, taking physics!

But seriously, if the time were 4 seconds, then yes the answer would be 90m. I reckon the book's wrong, because you're told it's 3 seconds.