Problema Solution
Two cars, 360 kilometers apart, begin driving toward each other on a long, straight highway. One car travels 80 kilometers per hour and the other 100 kilometers per hour. At the same time, a canary, starting on one car, flies back and forth between the two cars as they approach each other. If the canary flies 120 kilometers per hour and spends no time to turn around at each car, how far has it flown when the cars collide?
Answer provided by our tutors
Let
v1 = 80 km/h the speed of the first car
v1 = 100 km/h the speed of the second car
v = 120 km/h the speed of the canary
d = 350 the distance between the cars in the beginning (when t = 0)
t = the time that the cars need to collide
Since the cars will collide that means that the total distance that they will pass is equal to d
v1*t + v2*t = d
80*t + 100*t = 360
t = 2 hours - the cars will collide after 2 hours
Since the canary is flying with speed v = 120 km/h after 2 hours that canary has flown v * t = 120 * 2 = 240 km.