HP 20S and HP 21S: Approximating Stopping Distances
Introduction
We can approximate the stopping distance (in feet) of a vehicle on dry pavement given the vehicle's speed (in miles per hour, mph) by the formula:
y = 3.85714285714*10^-2 * x^2 + 1.44504201681 * x + 0.64915966369
or
y = 27/200 * x^2 + 1.44504201681 * x + 0.64915966369
y: stopping distance on dry pavement, feet
x: speed of vehicle, mph
Assumptions:
* The vehicle is assumed to be a passenger vehicle.
* The reaction time is 1 second and the deceleration rate is 28 ft/s.
The program listed rounds all results to one decimal place.
HP 20S and HP 21S Program: Stopping Distance
The key codes for both calculators are the same in this program.
STEP KEY KEY CODE
01 LBL B 61, 41, b
02 STO 0 21, 0
03 x^2 51, 11
04 × 55
05 2 2
06 7 7
07 ÷ 45
08 7 7
09 0 0
10 0 0
11 + 75
12 RCL 0 22, 0
13 × 55
14 1 1
15 . 73
16 4 4
17 4 4
18 5 5
19 0 0
20 4 4
21 2 2
22 0 0
23 1 1
24 6 6
25 8 8
26 1 1
27 + 75
28 . 73
29 6 6
30 4 4
31 9 9
32 1 1
33 5 5
34 9 9
35 6 6
36 6 6
37 3 3
38 9 9
39 = 74
40 STO 1 21, 1
41 FIX 1 51, 33, 1
42 RTN 61, 26
Examples
Input: 25 mph, Result: 60.9 ft
Input: 40 mph, Result: 120.2 ft
Input: 65 mph, Result: 257.5 ft
Note: This time I am writing this blog entry direct in the Blogger compose box. When I transfer text from either Jarte or WordPad to Blogger, all the formatting is lost. And I don't want to format my text twice. I will still save a backup copy. I am very happy that Blogger compose box allows me to select special characters for the math symbols I need (the happy face is appropriate because it makes me happy!)
Source:
Introduction
We can approximate the stopping distance (in feet) of a vehicle on dry pavement given the vehicle's speed (in miles per hour, mph) by the formula:
y = 3.85714285714*10^-2 * x^2 + 1.44504201681 * x + 0.64915966369
or
y = 27/200 * x^2 + 1.44504201681 * x + 0.64915966369
y: stopping distance on dry pavement, feet
x: speed of vehicle, mph
Assumptions:
* The vehicle is assumed to be a passenger vehicle.
* The reaction time is 1 second and the deceleration rate is 28 ft/s.
The program listed rounds all results to one decimal place.
HP 20S and HP 21S Program: Stopping Distance
The key codes for both calculators are the same in this program.
STEP KEY KEY CODE
01 LBL B 61, 41, b
02 STO 0 21, 0
03 x^2 51, 11
04 × 55
05 2 2
06 7 7
07 ÷ 45
08 7 7
09 0 0
10 0 0
11 + 75
12 RCL 0 22, 0
13 × 55
14 1 1
15 . 73
16 4 4
17 4 4
18 5 5
19 0 0
20 4 4
21 2 2
22 0 0
23 1 1
24 6 6
25 8 8
26 1 1
27 + 75
28 . 73
29 6 6
30 4 4
31 9 9
32 1 1
33 5 5
34 9 9
35 6 6
36 6 6
37 3 3
38 9 9
39 = 74
40 STO 1 21, 1
41 FIX 1 51, 33, 1
42 RTN 61, 26
Examples
Input: 25 mph, Result: 60.9 ft
Input: 40 mph, Result: 120.2 ft
Input: 65 mph, Result: 257.5 ft
Note: This time I am writing this blog entry direct in the Blogger compose box. When I transfer text from either Jarte or WordPad to Blogger, all the formatting is lost. And I don't want to format my text twice. I will still save a backup copy. I am very happy that Blogger compose box allows me to select special characters for the math symbols I need (the happy face is appropriate because it makes me happy!)
Source:
Glover, Thomas J. Pocket Ref 4th Edition. Sequoia Publishing, Inc. Littleton, CO. 2012
Eddie
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