Physics, 07.08.2021 16:50 gizmo50245
Một xe chạy trong 2 giờ với tốc độ trung bình 45 km/h rồi chạy tiếp 4 giờ với tốc độ trung bình 40 km/h. Tốc độ trung bình của xe trong cả quá trình chuyển động đó gần giá trị nào nhất sau đây?
Answers: 1
Physics, 21.06.2019 18:10
The difference between two numbers is 15. when twice the smaller number is subtracted from three times the larger number, the difference is 58.what is the larger number?
Answers: 1
Physics, 22.06.2019 06:20
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?
Answers: 1
Physics, 22.06.2019 12:50
Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.
Answers: 2
Một xe chạy trong 2 giờ với tốc độ trung bình 45 km/h rồi chạy tiếp 4 giờ với tốc độ trung bình 40 k...
Mathematics, 10.11.2019 06:31
Mathematics, 10.11.2019 06:31
Health, 10.11.2019 06:31
History, 10.11.2019 06:31
Mathematics, 10.11.2019 06:31
English, 10.11.2019 06:31