Consider an electrically heated brick house ( k = 0 .40 Btu/h .ft°F ) and whose walls are 9 ft high and 1 ft thick. Two of the walls of the house are 50 ft long and the others are 35 ft long. The house is maintained at 70°F at all times while the temperature of the outdoors varies. On a certain day, the temperature of the inner surface of the walls is measured to be at 55°F while the average temperature of the outer surface is observed to remain at 45°F during the day for 10 h and at 35°F at night for 14 h. Determine the amount of heat lost from the house that day. Also determine the cost of that heat loss to the homeowner for an electricity price of $0.09 kWh.
Consider an electrically heated brick house ( k = 0 .40 Btu/h .ft°F ) and whose walls are 9 ft high and 1 ft thick. Two of the walls of the house are 50 ft long and the others are 35 ft long. The house is maintained at 70°F at all times while the temperature of the outdoors varies. On a certain day, the temperature of the inner surface of the walls is measured to be at 55°F while the average temperature of the outer surface is observed to remain at 45°F during the day for 10 h and at 35°F at night for 14 h. Determine the amount of heat lost from the house that day. Also determine the cost of that heat loss to the homeowner for an electricity price of $0.09 kWh.
Solution Summary: The author calculates the amount of heat loss from the house on the day and also calculate the cost of that heat.
Consider an electrically heated brick house
(
k
=
0
.40 Btu/h
.ft°F
)
and whose walls are 9 ft high and 1 ft thick. Two of the walls of the house are 50 ft long and the others are 35 ft long. The house is maintained at 70°F at all times while the temperature of the outdoors varies. On a certain day, the temperature of the inner surface of the walls is measured to be at 55°F while the average temperature of the outer surface is observed to remain at 45°F during the day for 10 h and at 35°F at night for 14 h. Determine the amount of heat lost from the house that day. Also determine the cost of that heat loss to the homeowner for an electricity price of $0.09 kWh.
Hi, can you please define and calculate the failure mode of the linkage that failed on the swing (images added) :
A child swing set was discovered to have failed at the fixing at the top of the chains connecting the seat to the top of the swing set. A 12 mm threaded steel bolt, connecting the shackle to the top beam, failed at the start of the threaded region on the linkage closest to the outside side of the swing set .
The linkage and bolts were made of electro galvanised mild steel . The rigid bar chain alternatives and fixings were of the same material and appeared to be fitted in accordance with guidelines. The yield strength of the steel used is 260 MPa and the UTS is 380 MPa. The bolt that failed was threaded using a standard thread with a pitch (distance between threads) of 1.75 mm and a depth of approximately 1.1 mm.
The swing set in question had been assigned to ‘toddlers’ with the application of a caged-type seat. However, the location was within the play area not…
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11-68. The rectangular plate shown is subjected to a uniaxial
stress of 2000 psi. Compute the shear stress and the tensile
developed on a plane forming an angle of 30° with the longitud
axis of the member. (Hint: Assume a cross-sectional area of unity)
2000 psi
2000 psi
hp
11-70. A shear stress (pure shear) of 5000 psi exists on an element.
(a) Determine the maximum tensile and compressive stresses
caused in the element due to this shear.
(b) Sketch the element showing the planes on which the
maximum tensile and compressive stresses act.
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