Sunday, July 5, 2020

Casio fx-991EX and fx-115ES Plus: Velocity Conversions

Casio fx-991EX and fx-115ES Plus: Velocity Conversions

The Casio fx-991EX Classwiz and Casio fx-115ES Plus calculators, among others, have 40 conversions in various areas. 

Keystrokes

Keystrokes: Casio fx-115ES Plus

[ SHIFT ] [ 8 ], enter the required two digit code

The conversions we'll be working with this blog entry:

ft → m, 03
m → ft, 04
yd → m, 05
m → yd, 06
mile → km, 07
km → mile, 08
km/hr → m/s, 19
m/s → km/hr, 20

Keystrokes:  Casio fx-991EX Classwiz

[ SHIFT ] [ 8 ].    The conversions will be grouped by category (length, area, volume, etc).

ft → m, 1, 3
m → ft, 1, 4
yd → m, 1,5
m → yd, 1,6
mile → km, 1, 7
km → mile, 1, 8
km/hr → m/s, ↓, 1, 1
m/s → km/hr, ↓, 1, 2

km/hr  (kilometers per hour) vs mph (miles per hour)

The calculators mentioned does not have a direct conversion between km/hr and mph.  However, because the time frame is the same (per hour), we can use the km/mile conversions (since 1 hour = 1 hour and no time conversion part is required, only the length).

Example 1:  150 km/hr to mph

150 km>mile returns 93.20567884

150 km/hr = 9320567884 mph

Example 2:  65 mph to km/hr

65 mile>km = 104.60736

65 mph = 104.60736 km/hr

More Examples

Example 3:  5.8 ft/s to m/s

Again, since the time portion is the same (second to second), we only have to worry about length.

5.8 ft>m returns 1.76784

5.8 ft/s = 1.76784 m/s

Example 4:  110 ft/s to km/hr

Now we are converting both length and time.   There are no direct time conversions on the calculators featured, so we have to use the manual conversion. 

Remember that 1 hr = 3600 s and 1 km = 1000 m. To convert from m to km, divide by 1000 and to convert from 1/s to 1/hr, multiply by 3600 (note: 1/s to 1/hr)

(110 ft>m) ÷ 1000 × 3600 returns 120.7008

110 ft/s = 120.7008 km/hr

Example 5:  40 m/s to km/hr

Here is another example where we both have to convert the length (m to km) and time component (1/s to 1/hr).   This is similar to the Example 3.  However, the Casio calculators featured on this blog has conversions between m/s and km/hr (velocity section).

40 m/s>kh/hr returns 144 km/hr

40 m/s = 144 km/hr

Example 6:  100 ft^2 to m^2

The calculators have two area conversions (acre/m^2).   However, we can use the same length conversion twice to make other areas.

100 ft>m ft>m returns 9.290304

100 ft^2 = 9.290304 m^2

Example 7:  1 mi to yd by using the conversions available

(1 mi>km × 1000) m>yd returned 1760

(1 km = 1000 m)

1 mi = 1760 yd

A Cautionary Tale

Example 8:  1 acre to ft^2

1 acre>m^2 m>ft m>ft returns 43559.99545

However, as defined, 1 acre = 43560 ft^2. 

Lesson:  use caution when chaining conversions, 100% accuracy isn't guaranteed.

Eddie

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