Apologies if this seems like a stupidly obvious question.

Let's say that I model the trajectory of a projectile launched at some angle from the horizontal using a numerical approach which factors in all relevant forces (gravity and drag etc).

I have a list of data pertaining to the horizontal and vertical components of the displacement and velocity for some appropriate time step.

Now my question is, if I wanted to find out the direction (specifically the angle from the horizontal) that the projectile is going in (within the x-y plane) at any point in its flight, I would simply use trig like so?

$$\tan(\theta) = \frac{Vy}{Vx} $$

Where $Vx$ and $Vy$ are the horizontal and vertical velocities respectively for the instance of time that I was interested in - assuming I didn't care about interpolating the data for some instance of t that I did not have data for exactly.

E.g. if the projectile was moving 300 units in the Y direction and 50 units in the X direction at some time t, then it would be travelling approximately 80 degrees from the horizontal at t, right?


1 Answer 1


Yes. You are right.

In principle you would write

$$\tan(\theta)=\frac{\Delta y}{\Delta x}=\frac{\Delta y/\Delta t}{\Delta x/\Delta t}=\frac{V_y}{V_x}$$


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