Sir Isaac Newtons third law of motion applies to the golf swing.
"For for every action there is an equal and opposite reaction"
When you swing the golf club there is a force called Centrifugal Force pulling you towards the golf ball as this is the direction of the golf swing, this force can exceed up to as much as 50% of your body weight depending on the club you are using, the faster you swing the heavier the club gets and the stronger the centrifugal force becomes and so the more it tries to pull you over towards the ball!!
So one of three things will happen.....
1) You will be pulled forward in the direction of the swing towards the ball coming over the top & loosing balance!! This will cause you to swing on an out to in path producing a slice, pulls and poor contact, no matter how hard you try to stop it you cannot win this fight against Centrifugal Force!!
2) You will thrust your hips forward (this is also called early extension) in an effort to maintain your balance as Centrifugal Force pulls you over and your body's self preservation mechanism will kick in to keep you on your feet. This will also dramatically slow down your hip rotation through impact causing you to loose lag leading to a flick at the ball!! and for the better players you suffer with consistency issues and over rotation of the hands blocking to the right or pulling to the left!!
3) How can you win the battle against Centrifugal Force?? This is the ideal scenario but you cannot win!!! The golf swing is basically a game of tug of war! You are team A and team B is Centrifugal Force!! The key is to squat down to balance out the force pulling you forward!! Make sense now??You either equal or loose the game against Centrifugal Force!! You can see this happening with tour players watch their head closely and you will see how it lowers slightly on the downswing so they can harness the forces created from the swing.
Don't try and overpower or fight your friend Centrifugal Force or the laws of the universe as you will never succeed, but instead learn to harness them & see how your swing will flourish!!