Atrain sounds its horn as it approaches an intersection. the horn can just be heard at a level of 52 db by an observer 10 km away. (a) what is the average power generated by the horn? w (b) what intensity level of the horn's sound is observed by someone waiting at an intersection 56 m from the train? treat the horn as a point source and neglect any absorption of sound by the air. db

Are aliens real? justify you’re answer.

How is coal extracted from mountaintop removal mines? a. dynamite is used to create underground tunnels where miners go to extract the coal. b. dynamite is used to break apart rocks and then draglines are used to remove the broken rock and reach the coal. c. coal in mountaintops is extracted by digging strips in the landscape to reach the coal. d. placer deposits in mountain river bottoms are removed by

Abicycle slows down when the rider applies the brakes. what type of energy transformation is involved in this example? a. kinetic energy into heat energy b. heat energy into potential energy c. potential energy into kinetic energy d. kinetic energy into mechanical energy