According to huygens's principle, what is the explanation for boundary behaviors?

a.) each point on a wave front acts as a source of secondary waves.

b.) each point on a wave front stops moving as it progresses.

c.) each point on a wave front partly reflects and partly refracts the wave.

d.) most of the points on the wave front stop progressing.

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?

1.what is where an object is located 2. what is how fast an objects speed is changing 3. what is how fast an object is moving

If y gets smaller as x gets bigger and y have an relationship?