It exerts a downward force on the golf ball as soon as it is launched, a force that eventually brings it back to the ground. When the density of air is zero, such as in a vacuum, there is no friction. In this case, it is easy to compute precisely how long the golf ball remains airborne. The ball will follow a parabolic path as it fights gravity going up, and gives way to gravity on its return to the ground. We need only consider the vertical and horizontal velocity of the ball once it is hit to determine the distance the ball will travel along a parabolic path.
Friction introduces many complications in the calculation of the flight of a golf ball.
Because air is a viscous fluid, any object passing through it is subject to a drag force. The drag force depends upon the air density and the velocity of the ball. It also depends upon the size and shape of the golf ball. For many years, manufacturers have put small dimples on the face of the ball because these reduce the wake turbulence behind the ball that retards its motion. For the remainder of this discussion, we ll assume that the golf ball has standard size and shape.