Researchers at a university want to know if higher levels of nitrogen in fertilizer will increase the production of tomatoes per plant. twenty plants are given normal levels of nitrogen and twenty other plants are given ten percent higher levels throughout the growing season. the plants receive the same levels of sunlight, water and are planted in the same soil on one farm. at the end of the experiment the average number of tomatoes produced is the same for each group. the scientists repeat the experiment on two additional farms further south that season. the researchers conclude that increasing nitrogen levels by 10% in tomatoes is not beneficial. would this be a well-designed, reliable experiment? support your decision with at least three reasons.

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?

Which articulations allow for greatest range of motion?

A10 kg box initially at rest is pulled 18 meters across a horizontal, frictionless surface by a 40 n force. what is the block’s final velocity over the 18 meters?