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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