I want to create a small app describing projectile motion. Can anyone give some resources?
On this page... https://tumult.com/hype/tutorials/ ...there's the "Mastering Physics" template at the bottom. That has all sorts of information about Hype Physics. In particular, the "Cannon" scene might be what you're looking for.
Additionally, since you use the word "Describing", you might be interested in the "Physics" template, as that's used to explain the Physics settings in Hype.
The way the cannon fires is the best way to utilize the physics engine. Basically you set up an animation to kick off the movement and let the physics engine take it from there. For best results you should use a Linear or Ease In timing function; anything that eases out will result in it being pretty slow towards the end.
That said, the physics is a simulation and you aren't guaranteed to get the same results each time. This technique specifically does some time-based calculations when to determine the velocity hwen handing off to the physics engine, so different runs will have slightly different results based on CPU utilization. If you are going to teach a lesson it is may be better to hand animate.