### Brain Teasers

# Around the World

Two cars circumnavigate the world. Time is kept as they pass each other, travelling in opposite directions at the same speed of 70 miles per hour. The only difference is that one car is travelling on the surface of the planet, while the other is on a roadway 15 feet above ground.

Assuming the world is a perfect sphere and exactly 25,000 miles around, how much faster does the car travelling on the surface reach the original starting point?

Assume, for the sake of the puzzle, that there are 2 continuous, unobstructed, flat roadways around the earth and that the cars don't need gas, the drivers don't need 'pit stops', etc.

Assuming the world is a perfect sphere and exactly 25,000 miles around, how much faster does the car travelling on the surface reach the original starting point?

Assume, for the sake of the puzzle, that there are 2 continuous, unobstructed, flat roadways around the earth and that the cars don't need gas, the drivers don't need 'pit stops', etc.

### Hint

Circumference = 2*pi*r### Answer

The answer is only about 1 second!!!The circumference of the Earth is 2*pi*r. The circumference of the road 15 feet above the Earth is 2*pi*(r+15). The difference between these two distances is 2*pi*15 = 94 feet. This is how much further the car on the elevated roadway has to travel.

70 miles per hour is equal to 103 feet per second. At 103 feet per second, it will take the car on the elevated roadway just under one second to travel the extra 94 feet.

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