Problema Solution
A car traveling at 100 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 provided by our tutors
let
v1 = 100 km/h the speed of the first car
v2 = the speed of the second car
t = 30 sec = 30/(60*60) = 1/120 hr
since distance = speed*time in 30 second the first car will pass a distance of v1*30 and the second car will make a distance of v2*30
since the second car is faster the difference in the distances: v2t - v1t = 0.5 (since 500 m = 0.5 km)
(v2 - v1)t = 0.5
(v2 - 100)*(1/120) = 0.5
by solving we find:
v2 = 160 km/h
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the speed of the second car is 160 km/h.