Nice examples showing the power of App Inventor.
5 Likes
5.- Evaluate the definite integral with an error less than 1‰
- Function in Google
- Verification:
https://www.wolframalpha.com/widgets/view.jsp?id=1baf76735e53fba2b533ad071288344
p84Ei_integrales.aia (1.9 KB)
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
8 Likes
6.- Adapt this code to App Inventor to get moon age.
http://www.primaryhomeworkhelp.co.uk/moon/hemispheres.html
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
////////////////////////////////////////////////////////////////////////////////
//// CODE TO GET MOON AGE. Variable $jd //////////
///////////////////////////////////////////////////////////////////////////////
$day = Read($Input1)
$month = Read($Input2)
$year = Read($Input3)
$c = 0
$e = 0
$jd = 0
$b = 0
If ($month < 3) Then
$year = $year - 1
$month = $month + 12
EndIf
$month = $month + 1
$c = 365.25 * $year
$e = 30.6 * $month
$jd = $c + $e + $day - 694039.09 ; jd is total time
$jd = $jd / 29.5305882 ; divide moon cycle
$b = Int ($jd)
$jd = $jd - $b ; **$jd is MOON AGE**
$b = Round($jd * 8)
If ($b >= 8 ) Then $b = 0
Switch $b
Case 0
$fase = "Luna nueva"
Case 1
$fase = "Poco creciente"
Case 2
$fase = "Cuarto creciente"
Case 3
$fase = "Muy creciente"
Case 4
$fase = "Luna llena"
Case 5
$fase = "Poco menguante"
Case 6
$fase = "Cuarto menguante"
Case 7
$fase = "Muy menguante"
EndSwitch
GUICtrlSetData($Label5, $b & "-" & $fase)
10 Likes
7.- Solve two equations with two unknowns.
- Verify:
http://www.1728.org/unknwn2.htm
p84Di_dos_ecuaciones.aia (2.6 KB) (unfinished).
10 Likes
8.- Trigonometric projections of sine and cosine.
Drag your finger over the circle and get the horizontal and vertical projection of the radius.
radius = Canvas1.Width / 2
p7Yi2_proyecciones.aia (4.0 KB) (unfinished).
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
8 Likes
9.- Calculates the linear equation given two points.
- Information:
https://www.mathwarehouse.com/algebra/linear_equation/write-equation/equation-of-line-given-two-points.php - Verify:
https://www.mathsisfun.com/straight-line-graph-calculate.html
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
6 Likes
10.- Draw the Archimedean spiral.
r = a + b*θ
Let
a = 5
b = 4
θ in radians. Five 360º turnings.
p84Gi_espiral_arq.aia (2.3 KB) (unfinished).
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
8 Likes
11.- Using a Clock with a TimerInterval of 4 seconds, 7-bit digital random numbers are presented on a Label.
The user must click on the Button_0 or Button_1 to add the parity bit (even).
A Label shows whether the user's response is correct or not.
The number of bytes created and the number of correct answers must also be displayed.
p91i_crear_bit_paridad_juego.aia (3.5 KB) (unfinished).
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
6 Likes
12.- Pully on an incline with friction.
A 5 kg mass is placed on an incline with friction. Making an angle of 30 degrees with the horizontal. A rope is attached and positioned over a pulley at the top of the incline. A 6 kg mass is suspend from the free end. What is the acceleration of the system.
m1 going up or down?
Assume µ = 0.20
Information: https://www.youtube.com/watch?v=Fek9Pa2jQio
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
6 Likes
13.- Uniform Rectilinear Motion.
A green car starts and maintains a speed of 90 km/h in a straight line.
Another red car located 24 km, starts 2 hours later at a speed of 120 km/h
Calculate how long it will take to reach the green car.
Information: https://ekuatio.com/en/uniform-rectilinear-motion-solving-problems-step-by-step/
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
6 Likes
14.- Find the inverse of a given number.
Show number and result with multiples and submultiples prefix.
Information: https://www.medcalc.org/manual/decimal_multiples_and_submultiples_of_si_units.php
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
5 Likes
15.- Find the impedance and phase angle of a circuit RLC.
Information: https://www.youtube.com/watch?v=IVS-vjHdC1c
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
6 Likes
16.- Wheatstone bridge.
a) Create a random value for Rx.
b) Move the Slider until the volts are approximately zero.
c) Now Rx = R * (R2 / R1)
Information: https://www.youtube.com/watch?v=VbiOLkhQC4w
Information: https://en.wikipedia.org/wiki/Wheatstone_bridge
p82Ii_wheatstone.aia (18.4 KB) (unfinished).
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
8 Likes
17.- Limit of a function. Evaluate expression. Parse mathematical expressions.
To evaluate an algebraic expression we can use:
a) JavaScript: http://kio4.com/appinventor/168_javascript_evaluar_expresion.htm
b) JavaScript: https://groups.google.com/forum/#!category-topic/mitappinventortest/specific-programming-issue/0oVTthDFChY
c) Math extension by Taifun: https://puravidaapps.com/math.php
...but the proposal is to calculate the limits of these functions using only blocks.
- Example:
... when approaching value is 5, we can let x = 4.99999 or 5.00001
Information: https://www.mathwarehouse.com/calculus/limits/limits-indeterminate-factorable.php
Verification: https://www.dcode.fr/limit
Examples: https://www.matesfacil.com/BAC/limites/ejercicios-resueltos-limites-1.html
p78D_limites.aia (2.4 KB)
7 Likes
18.- Find the prime factors of a number.
Verification: https://www.dcode.fr/prime-factors-decomposition
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
8 Likes
19.- Statistical.
In a class of 18 students, they have obtained the following scores:
4,4,4,5,5,5,5,5,7,7,8,8,8,8,9,9,9,10.
Calculate the mean, variance and standard deviation of that distribution.
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
6 Likes
What an excellent library of exercises! Thanks for sharing it!
7 Likes
20.- Minimun surface.
An open-topped cylindrical container has a volume of V = 3140 cm3. Find the cylinder dimensions (radius of base r, height v) so that the least material is needed to form the container.
From: https://www.hackmath.net/en/math-problem/5891?tag_id=91&result=1
- Build an application using the expressions above.
- And with two sliders that move them calculate the surface keeping the volume constant. Check the minimum surface, in this case 942.16
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
5 Likes
On this website you can find many mathematical problems:
4 Likes
21.- Maximun angle.
The Statue of Liberty measures 46 m, is 47 m above ground level, look image.
What distance should one stand away from the statue in order to maximize the view of the statue? That is, what is the maximum angle Θ.
-
Build an application using the expressions above.
-
And with a Slider change value of x, get Θ and check the maximum angle Θ, in this case Θ = 19.18209º to x = 66.1 m
-
Information: https://www.slideshare.net/leingang/lesson-20-more-optimization-problems (pag. 20)
-
apk file in external link: http://kio4.com/appinventor/apk_archivos.htm
6 Likes