SOLUTION: A car traveling at 70 kilometers per hour is passed by a second car going in the same direction at a constant speed. After 30 seconds, the two cars are 500 meters apart. Find the s

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Question 758091: A car traveling at 70 kilometers per hour is passed by a second car going in the same direction at a constant speed. After 30 seconds, the two cars are 500 meters apart. Find the speed of the second car.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A car traveling at 70 kilometers per hour is passed by a second car
going in the same direction at a constant speed.
After 30 seconds, the two cars are 500 meters apart.
Find the speed of the second car.
:
let s = speed of the passing car
:
We're working km/hr:
change 500 m to 1%2F2 km
change 30 sec to 1%2F120 hrs
:
Write a distance equation; dist = speed * time
:
Passing car dist - 70 km/hr car dist = 500 meters
1%2F120s - 1%2F120(70) = 1%2F2
multiply eq by 120 to cancel the denominators, results:
1s - 1(70) = 120*1%2F2
s - 70 = 60
s = 60 + 70
s = 130 km/hr speed of the passing car
;
:
Confirm this by finding the distance each car traveled
1%2F120*130 = 1.08 km
1%2F120* 70 = .58 km
-------------------------
difference in dist: .5 km which is 500 m