HP 35s User Manual

							 
hp calculators 
 
HP 35s  General applications – Part 2 
 
hp calculators - 3 - HP 35s  General applications Part 2- Version 1.0 
 
Application 2: Electrical Engineering 
 
Example 1: Three resistors of 200 ohms, 500 ohms and 220 ohms are in parallel. What is the equivalent resistance? 
 
Solution: In RPN mode: !##3##34!!#343 
 In algebraic mode:33!##243##243!!#$ 

 Figure 2 
Answer: The equivalent resistance is 86.6 ohms 
 
Application 3: Civil Engineering 
 
Example 1: Runoff of rainfall from an area to an outlet will be at maximum when the water from the most remote point 
contributes to the flow. What is that time if the slope is 0.25 per foot per foot, the rain intensity is 0.8 inches 
per hour and the distance from the most remote area is 800 feet. Use a coefficient of 2.1 for grass. 
 
 The formula is: Time = C x ( D ÷ ( S x I 2 ) ) 1/3 
 
 Where C is the grass coefficient, D is the distance from the most remote area, S is the slope, and I is the 
rainfall intensity. 
 
Solution: In RPN mode: !-5$%##$
#-!$#-%*+&),67& 
 In algebraic mode:!-5&67,2%##)
4#-!&*+#-%$ 

 Figure 3 
Answer: The time until maximum is just under 36 minutes. 
 
   
						

							 
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hp calculators 
 
 
 
 
HP 35s  General applications - Part 3 
 
 
 
 
Other applications 
 
Practice solving problems 
 
- Application 1: True Heading 
 
- Application 2: Thrown object 
 
- Application 3: Gas Pressure 
 
 
 
   
						

							 
hp calculators 
 
HP 35s  General applications – part 3 
 
hp calculators - 2 - HP 35s  General applications – part 3- Version 1.0 
 
General applications 
 
This training aid will illustrate the application of the HP 35s calculator to several problems in other areas. These 
examples are far from exhaustive, but do indicate the incredible flexibility of the HP 35s calculator.  
Practice solving problems  
Application 1: True Heading 
 
Example 1: Before a plane takes off, a preflight plan must be filed indicating the proposed trip. In these plans, the 
known data are true course (TC), wind direction (WD), wind velocity (WV) and true air speed (TAS). Find 
the true heading of a planned flight, if TC = 80 degrees, WV = 55 mph, TAS = 180 mph, and the WD is 
toward 95 degrees. 
 
 The true heading = TC – ASIN ( WV x SIN ( WD – TC ) / TAS )  
Solution: Place the 35s into degrees mode by pressing 9! 
 
 In RPN mode: #$%%$&%$#(!#)*
****+,-* 
 In algebraic mode:**#,-%%+(&%#.)!#*
****$ 
*
 Figure 1 *
Answer: 75.46 degrees.   
Application 2: Thrown object 
 
Example 1: If a ball is thrown straight upward with a velocity of 95 feet per second, what is the velocity and height of the 
object after 2 seconds? Use a value of 32.2 feet per second per second for g. 
 
 Velocity = Original Velocity – g x time 
 
 Height = Original Velocity x time – ½ x g x t2 
 
Solution: In RPN mode: &%$/010$0+*(Velocity at t = 2 seconds) 
 
    &%$0+#1%$*
****/010+0,2***(Height at t = 2 seconds)* 
 In algebraic mode:**&%/010+0$**(Velocity at t = 2 seconds) 
*
    &%+0#1%+*
****/010+,20$**(Height at t = 2 seconds)*
*
*  
						

							 
hp calculators 
 
HP 35s  General applications – part 3 
 
hp calculators - 3 - HP 35s  General applications – part 3- Version 1.0 
 
 Figure 2 
 
 Figure 3 **
Answer: After 2 seconds, the object is at a height of 125.6 feet and traveling at a velocity of 30.6 feet per second.  
 
Application 3: Gas pressure 
 
Example 1: The internal pressure of a tank of gas is 1100 psi at room temperature (298 degrees Kelvin). What is the 
internal pressure if the temperature rises by 35 degrees Celsius? 
 
 New Pressure = Old Pressure x New Temperature ÷ Old Temperature 
 
Solution: In RPN mode: !!##$0&$/%3+0&*  
 In algebraic mode:**!!##+40&3/%.)0&$*
*
 Figure 4 **
Answer: The new pressure is 1229 psi.  
 
   
						

							 
hp calculators 
 
 
 
 
hp calculators 
 
 
 
 
HP 35s  Applications in Electrical Engineering 
 
 
 
 
Applications in electrical engineering 
 
Practice solving problems in electrical engineering 
 
- Application 1: Transmission line impedance 
 
 
 
   
						

							 
hp calculators 
 
HP 35s  Applications in Electrical Engineering 
 
hp calculators - 2 - HP 35s  Applications in Electrical Engineering - Version 1.0 
 
Applications in electrical engineering 
 
This training aid will illustrate the application of the HP 35s calculator to several problems arising in electrical 
engineering. These examples are far from exhaustive, but do indicate the incredible flexibility of the HP 35s calculator.  
Practice solving problems in electrical engineering  
Application 1: Transmission line impedance  
 The formulas below allow for the computation of the high frequency characteristic impedance for three 
types of transmission lines, where D is the input wire spacing, d is the wire diameter, ! is the relative 
permittivity, and h is the wire height.   
 Open two wire line  #
$%&
(d
2DLN
!
120Z0  Figure 1 
 
 Single wire near ground #
$%&
(d
4hLOG
!
138Z0  Figure 2 
 
 Coaxial line #
$%&
(d
DLN
!
60Z0  Figure 3 
 
 In the examples that follow, the HP 35s will be used to solve problems involving these equations. If 
repetitive calculations with these equations is foreseen, they could be entered into the HP 35s as equations 
and solved in that manner.  
 
Example 1: Compute Z0 for RG-218/U coaxial cable with D = 0.68 inches, d = 0.195 inches, and ! = 2.3 (polyethylene).  
Solution: In RPN mode: !#$%&(%!)#%*+,(-
----./0  
 In algebraic mode:--!($%&10./-
----%!)(%*+,-
----# 
-
 Figure 4 -
Answer: 49.42 ohms.   
Example 2: Compute Z0 for an open 2-wire line with D = 6 inches, d = 0.0808 inches, and ! = 1 (air).  
Solution: Note that the division by the square root of 1 in the solutions below is unnecessary, but included for clarity. 
 
 In RPN mode: *$#*(!#$0%))(-
----./0  
 In algebraic mode:--*$(*10./!0$(%))-
----#-  
						

							 
hp calculators 
 
HP 35s  Applications in Electrical Engineering 
 
hp calculators - 3 - HP 35s  Applications in Electrical Engineering - Version 1.0 
 
 
 Figure 5   
Answer: 600.08 ohms.  
 
Example 3: Compute Z0 for an air line consisting of a single 0.1285 inch wire six inches from a ground plane.  
Solution: Note that ! = 1, since this is an air line. 
 
 In RPN mode: *&)#*(2#!0%*$),(-
----340  
 In algebraic mode:--*&)(*103420!(%*$),-
----# 
 
 Figure 6   
Answer: 313.44 ohms.