A woman is sitting at a bus stop when an ambulance with a siren wailing at 430 Hz approaches at 31.0 m/s (about 69 mph). Assume the speed of sound to be 343 m/s. (a)
What frequency (in Hz) does the woman hear?
fa = Hz
With what speed vs (in m/s) would the ambulance have to travel in order for the woman to hear the siren at an apparent frequency of fa = 451 Hz?
vs = m/s

What frequency (in Hz) would the woman hear if the siren moved away from her with the same speed you found in part (b)?
fa = Hz

Clothing made of several thin layers of fabric with trapped air in between, often called ski clothing, is commonly used in cold climates because it is light, fashionable, and a very effective thermal insulator. so it is no surprise that such clothing has largely replaced thickand heavy old-fashioned coats. (a) consider a jacket made of five layers of 0.1-mm-thick synthetic fabric (k = 0.13 w/m·°c) with 1.5-mm-thick air space (k = 0.026 w/m·°c) between the layers. assuming the inner surface temperature of the jacket to be 28°c and the surface area to be 1.25 m2, determine the rate of heat loss through the jacket when the temperature of the outdoors is 0°c and the heat transfer coefficient at the outer surface is 25 w/m2·°c. (b) what would your response be if the jacket is made of a single layer of 0.5-mm-thick synthetic fabric? what should be the thickness of a wool fabric (k = 0.035 w/m·°c) if the person is to achieve the same level of thermal comfort wearing a thick wool coat instead of a five-layer ski jacket?

How are series and parallel circuits simililar? both have multiple paths for electrons to travel. both require resistors in their circuits. both require a switch to complete the circuit. both have at least one path for electrons to travel.

What is an example of static friction