💯An Ingelious Way to Understand Kinematics Projectile Motion Questions

Kinematics Projectile Motion

Here’s an “ingelious” way to understand JC A Level H2 Physics projectile motion related to kinematics.
Let’s try to derive the optimum angle to throw a javelin for maximum range, assuming no air resistance:

The distance travelled by a projectile is always determined by its time of flight .
Its time of flight is in turn determined by its initial vertical velocity .
Note is the same for both horizontal and vertical motion.
To find its time of flight, let the vertical displacement be 0 (when the javelin returns back to ground)
Set upwards as positive,