Just For Fun
Have a guess
Imagine that the world has no seas, oceans or mountains, in other words fairly flat. I now start a journey following the equator all around the earth uncoiling a length of rope. When I arrive back to where I started, my intention is to join both ends of the rope thereby completely encircling the earth. Unfortunately the rope is approximately 1 yard short. In order for me to now join the ends I will have to go all around the world again removing earth from under the rope, in effect digging a small trench. The question, how deep will this trench have to be?
Adivinad
Imaginad que el mundo no tiene mares, océanos y montañas, en efecto, bastante plano. Viajo al rededor del ecuador desenrollando un trozo de cuerda. Cuando llego de nuevo a donde empecé, la intención es juntar los dos extremos de la cuerda. Así la cuerda habrá rodeado la tierra. Por desgracia la cuerda falta 1 metro. Para unir los dos extremos, tendré que viajar por todo el mundo una vez más, quitando un poco de la tierra de debajo de la cuerda, en efecto, cavar una pequeña zanja. La pregunta, qué tan profunda será esta trinchera?
4 Answers
r1 = radius at the equator
r = radius needed
circumference is calculated by 2pir
so:
2pir1 – 3ft = 2pir
2pir1 – 2pir = 3ft
r1 – r = 3ft/2pi
r1 – r = 0.477ft = 5.73 in
Hi Izanoni
Correct answer, but doesn´t it seem unreal that you would have to excavate almost a full six inches all the way around the world just to make up that missing yard.
In short it doesn´t matter what the size of the circle is. Due to the relationship with the diameter and the circumference, if you reduce the circumference by 3 feet you reduce the diameter by 1 foot (approx), which reduces the radius by six inches (approx).
one yard?
Doesn´t anyone fancy a guess? You will be surprised at the answer.
