1. Los hornos de microondas utilizan radiación de microondas para calentar los alimentos. La energía de las microondas es absorbida por las moléculas de agua de los alimentos, y después se transfiere a los demás componentes de los alimentos. a) Suponga que la radiación por microondas tiene longitud de onda de 11.2 cm. ¿Cuántos fotones son necesarios para calentar 200 mL de café de 23°C a 60°C, que equivale a una energía total de 3.1x10^4 J?

b) Suponga que la potencia de las microondas es de 900W (1 Watt= 1 J/s). ¿Por cuanto tiempo tendría que calentar el café en el caso del inciso a)?

answer: f

explanation: g

the answer is b, have negligible mass

it doesn't. it was imagined up in the middle ages.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.