During the trip from A to B, a train stopped for 10 minutes. For the train to arrive in time to B, the train's speed was changed to be 6km/sec faster than before. If the distance from A to B is 60 km, find the first train speed. After the 10 minute stop the speed was increased to 6 km/sec faster, and the train stopped exactly inbetween (30km from A)
2007-05-26 18:06:37 · 6 answers · asked by Mongolian Warrior 3 in Science & Mathematics ➔ Mathematics
Find the speed of the train before he stopped
2007-05-26 18:18:23 · update #1
6km/hour
And I dont know the answer, if i did why would i post it here?
2007-05-26 18:34:05 · update #2
First train speed means first speed of the train isnt it?
You dont mention how long it means to arrive in time so I will presume that it is T seconds. Remember that 10 minutes is 600 seconds. Assume that the first run time is t so the second run time is T-600-t.
Assuming the first speed is v, the total distance equation is
60 = Distance Before Stop + Distance After Stop
60 = vt + (v+6)(T-600-t)
60 = vt + (v+6)T - (v+6)600 - (v+6)t
60 = -6t +Tv + 6 - 600v - 3600
3660-6T= -6t + (T-600)v
from the information that the train stopped 30km from A, we can imply that
30 = vt, v=30/t
Use subtitution
3660-6T = -6t + (T-10) 30/t
multiply both side by t and you got :
(3660-6T)t = -6t^2 + (T-10)30
6t^2+ (3660-6)t - (30T-300)
The next step will be too complicated without knowing the value of T, so please just enter the value of T and do the rest with ABC technique.
2007-05-26 18:40:10 · answer #1 · answered by seed of eternity 6 · 0⤊ 0⤋
are you sure that's km/sec? maybe km/hr? 6km/sec is 21,600 km/hr, faster than the speed of sound. too fast for a train.
assuming it's km/hr
assign a variable A to the first speed. assign a time T for the first half of the trip.
beacuse the 10 minute loss is made up for by an extra 6km/h
TxA=30km
(T-1/6hr)x(A+6km/hr)=30km
with two equations and two unknowns you solve the first equation like T=30/A and put that into the second equation instead of T.
Then sove for A
2007-05-27 01:24:12 · answer #2 · answered by Piglet O 6 · 1⤊ 0⤋
first of all, no train in this reality can accelerate and go 6km/sec.....you need total time or more information to complete correct problem
2007-05-27 01:22:11 · answer #3 · answered by yourdaddy0 2 · 0⤊ 0⤋
umm...... find the first trains speed? there is only one train isnt there?
2007-05-27 01:11:44 · answer #4 · answered by doug_johnson39 2 · 0⤊ 1⤋
Yeah your teacher
2007-05-27 01:14:36 · answer #5 · answered by cabron o 4 · 0⤊ 1⤋
do YOU know the answer?
"yourdaddy0" is right
2007-05-27 01:23:39 · answer #6 · answered by kiki 1 · 0⤊ 1⤋