The sound from the whistle of a truck moving at 17.0 m/s toward a ...

[mcmcdaniel]

The sound from the whistle of a truck moving at 17.0 m/s toward a cliff reflects from the cliff and is heard by the driver of the truck. When it is parked at the side of the road, the whistle from the truck produces sound of frequency 2.267 kHz.
 
  As observed by the driver of the truck, what is the change in frequency the sound from the whistle due to the reflection? The speed of sound is 343 m/s. A) 236 Hz
  B) 228 Hz
  C) 207 Hz
  D) 118 Hz
  E) 472 Hz

Question 2

The thermal conductivity of a certain concrete is 0.80 W/m . K and the thermal conductivity of a certain wood is 0.10 W/m  K.
 
  How thick would a solid concrete wall have to be in order to have the same rate of heat flow through it as an 8.0-cm thick wall made of solid wood? Both walls have the same surface area and the same temperature difference across their faces.
  A) 53 cm
  B) 64 cm
  C) 71 cm
  D) 85 cm

[SAUXC]

Answer to Question 1

A

Answer to Question 2

B