# In a home, air infiltrates from the outside through cracks around doors and windows. Consider a residence where the total length of cracks is 62 m and the total internal volume is 210 m3 . Due to the wind, 9.4 x 10-5 kg/s of air enters per meter of crack and exits up a chimney. Assume air temperature is the same inside and out and air density is constant at 1.186 kg/m3 . If windows and doors are not opened or closed, estimate the time required for one complete air change in the building.

Time period  = 41654.08 s

Explanation:

Given data:

Internal volume is 210 m^3

Rate of air infiltration

length of cracks 62 m

air density = 1.186 kg/m^3

Total rate of air infiltration

total volume of air  infiltration

Time period

## Related Questions

Why do we care about a material's ability to resist torsional deformation?(A) Because the angle of twist of a material is often used to predict its shear toughness
(B) Because rotating shafts are used in engineering applications
(C) We don't care - simply an academic exercise.
(D) Because it can determine G and inform us of a materials ability to resist shear deformation

(A) Because the angle of twist of a material is often used to predict its shear toughness

Explanation:

In engineering, torsion is the solicitation that occurs when a moment is applied on the longitudinal axis of a construction element or mechanical prism, such as axes or, in general, elements where one dimension predominates over the other two, although it is possible to find it in diverse situations.

The torsion is characterized geometrically because any curve parallel to the axis of the piece is no longer contained in the plane initially formed by the two curves. Instead, a curve parallel to the axis is twisted around it.

The general study of torsion is complicated because under that type of solicitation the cross section of a piece in general is characterized by two phenomena:

1- Tangential tensions appear parallel to the cross section.

2- When the previous tensions are not properly distributed, which always happens unless the section has circular symmetry, sectional warps appear that make the deformed cross sections not flat.

You are analyzing an open-return wind tunnel that intakes air at 20 m/s and 320K. When the flow exits the wind tunnel it is moving at a speed of 250 m/s. What is the temperature of the flow exiting that wind tunnel

The solution is in the attachment

Explanation:

An inflatable structure has the shape of a half-circular cylinder with hemispherical ends. The structure has a radius of 40 ft when inflated to a pressure of 0.60 psi. A longitudinal seam runs the entire length of the structure. The seam fails in tension when the load is 600 pounds per inch of seam. What is the factor of safety with respect to longitudinal seam failure?

Find the given attachment

The compressibility factor provides a quick way to assess when the ideal gas law is valid. Use a solver to find the minimum temperature where the fluid has a vapor phase compressibility factor greater than 0.95 at 3 MPa. Report the value in oC, without units.

Explanation:

The compressibility factor

If new research showed that the standard heights for crest vertical curve design were H1=3.0 ft and H2=1.5 ft, respectively, by what percent would the minimum length of curvature increase or decrease for a crest curve with a stopping sight distance of 500 ft and grades of +3% and -2%, respectively.

A = 5

S<L, L = 714.89ft

S>L, L = 650.29ft

L = 115.85ft

Percentage min. Length of curvature = 6.2 %

Explanation: see explanation at the attached file

An escalator with 35° incline is designed to have two passengers per step. Find number of persons moved per hour for the design if velocity is 50cm/mins and the step tread is 600mm.

The escalator disposes 58 passengers each hour.

Explanation:

The velocity diagram of the escalator is shown in the attached figure

We can obtain the vertical distance that the escalator moves in 1 hour as

Thus in 1 hour the last thread moves 1720.73 cm

Now it is given that 1 thread = 600 mm =60 cm

Thus the number of times the last thread moves equals

Since each time last thread moves it disposes 2 passengers thus the number of passengers disposed when the thread moves 28.68 times equals

Thus the escalator disposes 58 passengers each hour.