Launch a projectile and mark its position at the end of every second. Count outward from the highest point of its path. The vertical gaps come out as 5 metres, then 15, then 25, then 35. Launch it faster and those numbers stay exactly the same. The last second before the projectile reaches the top is always about 5 metres.
Set the launch with u_x and u_y, or with u and θ. Press Play to launch — there is no separate launch button. Choose Continuous to run straight through, or Step to pause at every mark and move on with Next. Gravity is fixed at 10 here so the numbers stay clean. Reset unlocks the sliders and clears the marks.
A dot at each whole second, counted outward from the top. Below the x-axis, the horizontal gaps — all equal, all the same as u_x. Beside the y-axis, the vertical gaps on the way up — squeezing closer as the projectile nears the top. The moving ball carries its vₓ and vᵧ values with it; vₓ never changes and vᵧ drops by 10 every second. Leftover part-seconds at the start and end are labelled with how long they actually lasted, like 15 (0.5s), rather than being rounded away.
No air resistance. Gravity is fixed at 10. Only the upward gaps are labelled — the way down mirrors them exactly.
You should be able to say why the vertical gaps get smaller near the top while the horizontal ones stay the same.