1. Bob needs to go to his friend’s house which is 1.2 miles down 4th street and 3 miles down main. To complete this task, he goes into his car and builds a car that is engineered to get out of his driveway, drive 1.2 miles down 4th, take a 90 degree turn then go 3 miles down Main. Bob did get to his friends house, but has to re-engineer his car to drive the way back. To Bob’s dismay, his mother gives him a call and wants him to visit. While Bob loves his mother, he does not remember the way to her house, he can not remember if he needs to take a right at Maple or a left at Maple. He will know once he gets there though because there is an ugly tree next to where he needs to turn. So Bob will have to re-engineer his entire car on the road when he knows which way to go.
2. Frank wants to his friend’s house. Frank, like bob, does not remember the exact way. To get around this solution frank builds a car with wheels that move forward when a pedal is hit, they can also turn when a wheel inside the car is turned. This way Frank can use the car to go exactly where he tells it to. And when he gets home, he can use it again!