Q: Reconsider Prob. 20–37. In order to reduce the
Reconsider Prob. 20–37. In order to reduce the heating cost of the hot water, it is proposed to insulate the side and bottom surfaces of the container with 5-cm-thick fiberglass insu...
See AnswerQ: An office worker claims that a cup of cold coffee on his
An office worker claims that a cup of cold coffee on his table warmed up to 80°C by picking up energy from the surrounding air, which is at 25°C. Is there any truth to his claim? Does this process vio...
See AnswerQ: A 150-lbm astronaut took his bathroom scale (a spring
A 150-lbm astronaut took his bathroom scale (a spring scale) and a beam scale (compares masses) to the moon, where the local gravity is g = 5.48 ft/s2. Determine how much he will weigh (a) on the spri...
See AnswerQ: The pump of a water distribution system is powered by a 15
The pump of a water distribution system is powered by a 15-kW electric motor whose efficiency is 90 percent. The water flow rate through the pump is 50 L/s. The diameters of the inlet and outlet pipes...
See AnswerQ: A 10-cm-diameter, 30-cm-high
A 10-cm-diameter, 30-cm-high cylindrical bottle contains cold water at 3°C. The bottle is placed in windy air at 27°C. The water temperature is measured to be 11°C after 45 min of cooling. Disregardin...
See AnswerQ: A room is to be heated by a coal-burning stove
A room is to be heated by a coal-burning stove, which is a cylindrical cavity with an outer diameter of 50 cm and a height of 120 cm. The rate of heat loss from the room is estimated to be 1.5 kW when...
See AnswerQ: A stainless steel ball (ρ = 8055 kg/m3,
A stainless steel ball (ρ = 8055 kg/m3, cp = 480 J/kg⋅K) of diameter D = 15 cm is removed from the oven at a uniform temperature of 125°C. The ball is then subjected to the flow of air at 1 atm pressu...
See AnswerQ: When will the hull of a ship sink deeper in the water
When will the hull of a ship sink deeper in the water: when the ship is sailing in fresh water or in seawater? Why?
See AnswerQ: Reconsider Prob. 19–51. Using appropriate software, investigate
Reconsider Prob. 19–51. Using appropriate software, investigate the effect of air velocity on the average convection heat transfer coefficient and the cooling time. Let the air velocity vary from 1 m/...
See AnswerQ: Consider a cylinder with a length of 15 cm and a diameter
Consider a cylinder with a length of 15 cm and a diameter of 10 cm. The cylinder has a surface temperature of 43°C, while the room air temperature is 17°C. Determine whether placing the cylinder horiz...
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