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Projectile motion step by step solver — a TI-84 Plus CE program

By E-Code · updated

PROJSTEP is a TI-BASIC program for the TI-84 Plus CE. Launch speed and angle (degrees, from the ground, g = 9.8 m/s²) worked one step per screen, so you can copy the working: split the velocity into VX and VY, time to the top, max height, flight time, range, then a summary.

What it asks for and what it shows

It asks for 2 values at its prompts. In the example below it shows T (S), H (M), R (M), STEP 1 OF 5, SPLIT VELOCITY, VX, =20*COS(35°), VX, VY, =20*SIN(35°), VY, STEP 2 OF 5, TIME TO THE TOP, AT THE TOP VY, TUP, =11.472/9.8, TUP, STEP 3 OF 5, MAX HEIGHT, H, =11.472²/19.6, H, STEP 4 OF 5, FLIGHT TIME, UP AND BACK DOWN, T, =2*1.1706, T, STEP 5 OF 5, RANGE, R, =16.383*2.3411, R, SUMMARY, G.

Example run

One of its oracle test cases. The inputs are typed in order, and the results are the values the case expects on the screen.

StepValue
You enter
Input 120
Input 235
The screen shows
T (S)=2.341128312
H (M)=6.71408017
R (M)=38.35480085
TextSTEP 1 OF 5
TextSPLIT VELOCITY
VX=V*COS(θ)
Text=20*COS(35°)
VX=16.383
VY=V*SIN(θ)
Text=20*SIN(35°)
VY=11.472
TextSTEP 2 OF 5
TextTIME TO THE TOP
AT THE TOP VY=0
TUP=VY/G
Text=11.472/9.8
TUP=1.1706
TextSTEP 3 OF 5
TextMAX HEIGHT
H=VY²/(2G)
Text=11.472²/19.6
H=6.7141
TextSTEP 4 OF 5
TextFLIGHT TIME
TextUP AND BACK DOWN
T=2*TUP
Text=2*1.1706
T=2.3411
TextSTEP 5 OF 5
TextRANGE
R=VX*T
Text=16.383*2.3411
R=38.355
TextSUMMARY
G=9.8 M/S²

How it's checked

5 test cases, each checked against an independent method. Replayed key by key on a virtual TI-84 Plus CE, they make 152 checks.

How E-Code checks every program

Run it or put it on your calculator

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