SOLUTION: a car 15 feet long overtakes a truck 30 feet long which is traveling at the rate of 45 miles per hour. how fast must the car travel to pass the truck in 3 seconds?

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Question 285014: a car 15 feet long overtakes a truck 30 feet long which is traveling at the rate of 45 miles per hour. how fast must the car travel to pass the truck in 3 seconds?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Let the speed of the car be x feet/sec
Truck speed = 45 mph
The effective speed of the car is x-45 mph ( because they are in the same direction)
The car has to travel 15feet +30 feet to completely pass the truck = 45 feet
45 mph =66 ft/sec
Speed = distance / time

x-66 = 45 / 3
x-66=15
x=66+15
x= 81 ft/sec
=55 mph