Calcule la frecuencia fundamental y la de los tres primeros sobre tonos de un tubo de 45 cm de longitud a.) si está abierto en ambos extremos; b.) si está cerrado en un extremo. Use v=344 m/s; c.) determine el número del armónico más alto que podrá oír una persona con oído normal (que puede oír a frecuencias de 20 a 20,000 Hz) para cada uno de los casos anteriores.

Aball is thrown upward in the air, and its height above the ground after t seconds is h ( t ) = 57 t − 16 t 2 feet. find the time t when the ball will be traveling upward at 14.25 feet per second.

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Ametal ring 4.20 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpendicular to the magnetic field. these magnets produce an initial uniform field of 1.12 t between them but are gradually pulled apart, causing this field to remain uniform but decrease steadily at 0.240 t/s . (a) what is the magnitude of the electric field induced in the ring? (b) in which direction (clockwise or counterclockwise) does the current flow as viewed by someone on the south pole of the magnet?