## 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,

It is good practice not to change the sign of the formula, but use

or

Since range

Since are constants,

To maximise ,

,