9. A student notices that wearing darker colors in sunlight makes him feel warmer, so he decides to conduct an experiment. He takes five pieces of different colored cloth and wraps
each one around a water bottle. He then places all five bottles in direct sunlight and measures the temperature of the water in each bottle an hour later
What is the dependent variable in this experiment?
O the time he leaves it in the sunlight
O the amount of water in each bottle
O the color of the cloth
O the temperature of the water

Free runners jump long distances and land on the ground or a wall. how do they apply newton’s second law to lessen the force of impact?

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?

Select all the correct answers. which three statements about electromagnetic radiation are true?