SabateWeb.com - Quiz

El elefante y la Pluma

jmsabate@sabateweb.com (Josep Maria Sabate) — Dom, 28 Ago 2011 19:15:17 +0000

Las leyes de Newton. Caida libre

El Elefante y la Pluma

Suppose that an elephant and a feather are dropped off a very tall building from the same height at the same time. Suppose also that air resistance could be eliminated such that neither the elephant nor the feather would experience any air drag during the course of their fall. Which object - the elephant or the feather - will hit the ground first? The animation at the right accurately depicts this situation. The motion of the elephant and the feather in the absence of air resistance is shown. Further, the acceleration of each object is represented by a vector arrow.

Many people are surprised by the fact that in the absence of air resistance, the elephant and the feather strike the ground at the same time. Why is this so? This question is the source of much confusion (as well as a variety of misconceptions). Test your understanding by making an effort to identify the following statements as being either true or false.

TRUE or FALSE:

How Much did the Samples Weigh?

jmsabate@sabateweb.com (Josep Maria Sabate) — Dom, 28 Ago 2011 19:00:49 +0000

How Much did the Samples Weigh?

A chemistry professor asked his graduate student to find the weights of five different samples of an unknown material.

The student weighed each possible pair of samples, and recorded the weight of each pair as 120, 110, 117, 112, 115, 113, 114, 121, 116, and 118 grams. When he tried to figure out the five individual weights, he realized that he had neglected to record which samples made up each pair.

The professor said that he could figure out the five weights from the data the student had already collected.

How much did the samples weigh?

How many Weighings for N coins?

jmsabate@sabateweb.com (Josep Maria Sabate) — Dom, 28 Ago 2011 18:57:44 +0000

How Many Weighings for N Coins?

Mike Boughton wrote the original puzzle:

> There is an old one called the 12 penny problem: You have 12 coins, all
> apparently alike, but one is either heavier or lighter. Your job is to
> find which and which one in 3 weighings on a balance using only the coins
> themselves.
>
> This version does not require any math. Somehwere I saw a response that
> does. Not only did it contain the solution for 12, which takes a few
> minutes to figure out, but the general solution of how many weighings it
> takes for n coins.

Cuantos patos pesa el gato?

jmsabate@sabateweb.com (Josep Maria Sabate) — Sáb, 27 Ago 2011 19:32:30 +0000

Cuantos patos pesa el gato?

Facil 1

jmsabate@sabateweb.com (Josep Maria Sabate) — Sáb, 27 Ago 2011 18:46:38 +0000

• (Señale la balanza B.) ¿Que hay en la balanza B? (una esfera) ¿Cuánto pesa? (seis libras)
• (Señale la balanza A.) ¿Que hay en la balanza A? (un cubo y una esfera) ¿Cuánto pesan los objetos a la vez? (nueve libras)
• Calcule el peso del cubo. ¿Cómo lo hiciste? (La esfera es de 6 libras, así que el cubo pesa 9 -. 6, o tres, libra)

Facil 2

jmsabate@sabateweb.com (Josep Maria Sabate) — Sáb, 27 Ago 2011 19:04:08 +0000

Dibuje dos balanzas (figura 2.3) en la pizarra o en una cartulina. Al igual que en el problema 1, el peso de un bloque se da en este problema. Pero a diferencia de en el problema 1, para encontrar el peso de un cubo, deben realizarse dos operaciones. En primer lugar determinar el peso total de los cubos. Haga las siguientes preguntas:
• ¿Qué bloque hay en la balanza A? (una esfera)
• ¿Cuál es el peso de la esfera? (cuatro libras) ¿Cómo lo sabes? (La balanza muestra cuatro libras.)
• (Señale la balanza B.) ¿Cuál hay en labalanza B? (una esfera y dos cubos)
• ¿Cuánto pesan los bloques a la vez? (catorce libras)
• (Punto de la esfera en la escala B) ¿Cuánto pesa la esfera? (cuatro libras)
• ¿Cómo se puede saber cuánto pesa cada cubo? (La esfera pesa cuatro libras. Asi que losdos cubos pesaran 14 - 4, osea diez libras Así que cada cubo pesa cinco libras.)

3 y 2 son 6

jmsabate@sabateweb.com (Josep Maria Sabate) — Jue, 25 Ago 2011 19:00:45 +0000

A pesar de que ambos lados de la balanza tiene dos protones y tres neutrones, los productos de fusión de la derecha han perdido algo de masa. La masa perdida, se pierde con la energía liberada. La cantidad exacta se puede calcular por la famosa ecuación de Albert Einstein, E = mc2.