Raxit85 wrote:
Bunuel wrote:
Mo2men wrote:
SOLUTIONIf Car X followed Car Y across a certain bridge that is 1/2 mile long, how many seconds did it take Car X to travel across the bridge?Let the time needed for car X to travel across the bridge be \(t_x\) seconds and the time needed for car Y be \(t_y\) seconds.
(1) Car X drove
onto the bridge exactly 3 seconds after car Y drove onto the bridge and
drove off the bridge exactly 2 seconds after car Y drove off the bridge --> car X needs 1 second less to travel across the bridge than car Y -->
\(t_y=t_x+1\). Not sufficient to calculate \(t_x\).
Dear
BunuelHow did you infer or conclude that relation in statement 1? I'm not able to understand it.
Thanks
Highlighted portion should help. Car X was on the bridge 3 seconds
after car Y, but off the bridge only 2 seconds
after car Y. So, X was on the bridge 1 second less than car Y.
Bunuel /
chetan2u /
JeffTargetTestPrep,
I still face the confusion in understanding the phrases and visualization.
Earlier: X was behind the Y and difference in time was 3 seconds,
Later: X was still behind the Y and difference in time was 2 seconds, implying that speed of X must be more than speed of Y to compensate 1 second.
D R T
X: 0.5 >30 t
Y: 0.5 30 t+x
Now i stuck. Can you please help me?
Thanks!
Take Y DRT : 0.5—30—(t+1)....t+x is t+(3-2) or t+1. Find t from this and that is you answer.
We are interested in just time, so we should concentrate on time.
We know speed and distance for Y, which will give us time taken by Y.
Time taken by X is 1 second less, so subtract 1 from the above found time.