Saturday, September 4, 2021

Sharp EL-5500III & PC-1403: Stairs and Air Density and Viscosity

 Sharp EL-5500III & PC-1403:  Stairs and Air Density and Viscosity


Stairs


Inputs:

RISE:  The floor-to-floor rise of the staircase. 

MAX RISER HGHT:  The maximum allowable rise height.

TREAD WIDTH:  The desired tread width of each stair.


Outputs:

N:  Number of Stairs

TRUE RH:  True riser height of the stair

# TREADS:  Number of treads

RUN:  Total theoretical run from the first stair to the top.

INCLINE:  Incline of the stair in degrees

STRINGER:  Length of the stringer


All amounts are assumed to be in inches and all amounts are precise (no rounding to the nearest 1/8th inch or 1/16 inch, etc).


Sharp EL-5500III/PC-1403 Program:  Stairs

RUN 300 (or whatever line you designate)


300 PRINT "STAIRS"

303 DEGREE

306 INPUT "RISE (IN)? "; R

309 INPUT "MAX RISER HGHT? "; H

312 INPUT "TREADWIDTH? "; W

315 N = INT (R/H) + 1

318 PRINT "N = "; N

321 T = R/N

324 PRINT "TRUE RH = "; T; " IN"

327 E = N-1

330 PRINT "# TREADS = "; E

333 U = E*W

336 PRINT "RUN = "; U; " IN"

339 A = ATN (T/W)

342 PRINT "INCLINE = "; A

345 S = (E*W)/(COS A)

348 PRINT "STRINGER = "; S; " IN"

351 END


Example


Inputs:

RISE:  150 in   (12 ft 6 in)

MAX RISER HGHT: 7.5 in 

TREAD WIDTH:  12 in


Results:

N = 21

TRUE RH = 7.142857143 IN

# TREADS = 20

RUN = 240 IN

INCLINE = 30.76271954

STRINGER = 279.2994151 IN


Air Density and Viscosity


Inputs:

AIR (F):  Temperature of the air in degrees Fahrenheit (°F)

PRESSURE:  Air pressure in pounds per square inch (psia)


Outputs:

DENSITY:  Air density  (lbm/ft^3)

VISCOSITY:  Estimate of air viscosity (ft^2/sec)


The dynamic viscosity (μ) for air is estimated by the equation to three significant digits:


μ ≈ 5.550736842 * 10^-10 * F + 3.04406316 * 10^-7 


Table of viscosity values:  https://www.engineeringtoolbox.com/air-absolute-kinematic-viscosity-d_601.html


Sharp EL-5500III/PC-1403 Program:  Air Density and Viscosity

RUN 400 (or whatever line you designate)


400 PRINT "AIR DENSITY/VISC (US)"

403 INPUT "AIR (F)? "; F

406 INPUT "PRESSURE (PSIA)? ";R

409 D = (144*R) / (53.3533 * (F+459.67))

412 REM MU - 3 DEC APPROX

415 M = 5.550736842E-10*F + 3.404406316E-7

418 REM NEED 9 PLACES SINCE MU IS TO -6TH POWER

421 M = INT (M*TEN 9) / TEN 9

424 V = M*32.1740464/D

427 PRINT "DENSITY = ": PRINT D; " LBM/FT^3"

430 PRINT "VISCOSITY = ": RINT V; "FT^2/SEC"

433 END


Example


Inputs:

AIR (F):  78 °F

PRESSURE:  82 psia


Outputs:

DENSITY:  4.116226392E-01 LBM/FT^3

VISCOSITY:  2.993678821E-05 FT^2/SEC


Sources


"Air - Dynamic and Kinematic Viscosity".  The Engineering Toolbox   

https://www.engineeringtoolbox.com/air-absolute-kinematic-viscosity-d_601.html

Retrieved July 8, 2021


Lindeburg, Michael R. PE Practice Problems for the Civil Engineering PE Exam: A Companion to the Civil Engineering Reference Manual  Thirteenth Edition Professional Publications, Inc: Belmont, CA  2012


Eddie


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