Linear & Angular Force
In the golf swing, we use linear force, which is the force acting up and down the target line.
We also use angular force moving along a curved path and directed towards the axis of rotation.
So your downswing has two parts which you need to make happen first, the linear part, then the angular section.
So how this works is from the top of the swing, the club moves down, and imagine you are moving the handle end of the club parallel to the target line, in the linear force as seen in the photo demonstrated by Rory.
Linear is a downward force.
Next, when the handle has reached P.6, it begins working outward in the angular force, as you can see demonstrated by Tiger Woods.
Angular force is an outward force.