Sound waves travel at the rate of 343 m/s at 20°C. If a man standing 450 meters away from the wall of a canyon yells, “Hello,” how long will it take for him to hear his own voice echo off of the wall?

2.62seconds

Explanation:

Echo occurs when sound reflects and causing a delay before getting to the listener.

Let x be the distance from between the source and the reflector

t be the time taken for the echo to occur

v be the velocity of sound in air.

Using the relationship 2x = vt

t = 2x/v

Given x = 450metres

v = 343m/s

t = 2(450)/343

t = 900/343

t = 2.62seconds

It will take 2.62 seconds for him to hear his own voice echo off of the wall.

E cinetica = 140.24 [J] "unidades en Joules"

Explanation:

Para poder solucionar este problema debemos tener un dato aproximado de la masa de la pelota de beisbol, ya que en el problema este dato no fue dado, realizamos una busqueda por internet y encontramos que la masa de una pelota de beisbol es de aproximadamente m = 142 [gr].

Datos iniciales:

m = masa = 0.142 [kg]

v = velocidad = 160 [km/h]

debemos convertir de kilómetros por hora a metros por segundo.

Sabemos que la energia cinetica se define por medio de la siguiente ecuacion: