# Rate time distance

• Oct 14th 2012, 11:15 AM
CFY
Rate time distance
An elevator went from the bottom to the top of a 240 m tower, remained there for 12 seconds, and returned to the bottom in an elapsed time of 2 minutes. If the elevator traveled 1 m/s faster on the way down, find its speed going up.
• Oct 14th 2012, 11:48 AM
MaxJasper
Re: Rate time distance
240/sup+12+240/(sup+1) = 2*60(Itwasntme)
• Oct 14th 2012, 12:54 PM
CFY
Re: Rate time distance
thanks for your help. I tweaked your formaula a bit and found my answer; I was just unclear about what you meant by using "sup.:
• Oct 14th 2012, 01:09 PM
Soroban
Re: Rate time distance
Hello, CFY!

Quote:

An elevator went from the bottom to the top of a 240-m tower, remained there for 12 seconds,
and returned to the bottom in an elapsed time of 2 minutes.
If the elevator traveled 1 m/s faster on the way down, find its speed going up.

Let $S$ = speed going up (meters per second).
Then $S\!+\!1$ = speed going down.

The elevator went up 240 meters at $S$ m/sec.
. . This took: $\frac{240}{S}$ seconds.

Then it stopped for 12 seconds.

Then it went down 240 meters at $S\!+\!1$ m/sec.
. . This took: $\frac{240}{S+1}$ seconds.

The total time is 2 minutes (120 seconds).

The equation is: . $\frac{240}{S} + 12 + \frac{240}{S+1} \:=\:120$

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Nice "tweaking", CFY!
You saw that Max meant: . $\frac{240}{s_{up}} + 12 + \frac{240}{s_{up} + 1} \;=\;2\cdot60$