Answer to Question #83496 in Mechanics | Relativity for L

Question

What effect does air resistance have on a projectile?

Answer 1

Without air resistance, the horizontal component of a projectile (with respect to Earth) would be unchanged as it flew. It’s vertical component would increase in the direction of the gravity field as time continued. This creates a perfect parabola. As time increases, the object “falls” faster and faster but the speed across the ground remains unchanged.

With air resistance, neither component behaves in this way. The horizontal component will now decrease with time, in a decreasing manner. The effect of air resistance will be strongest initially as the horizontal velocity is at its maximum. As the horizontal component decreases, the effect of air resistance will also decrease but will always be there until the inertia is spent on the resistance. At this point the object will no longer move across the ground at all. The vertical component is trickier. The air resistance will continue to increase as the vertical component of the velocity increases, until the force of gravity and the air resistance on the object are equal. At this point the object has reached its “terminal velocity”. This point is different for every object as the air resistance and mass (and therefore gravitational force) are different for every object. A solid ball will have a higher terminal velocity than a feather.

So once the horizontal inertia is spent, the object stops moving across the ground, and once the air resistance matches the gravitational force the object will fall at a constant velocity.