Not quite correct. You must reduce one or the other or both, but you're really using the wrong equation. What you want to reduce is energy on impact. That is represented by the equation: 1/2MV^2, where M=mass, V=velocity.I think it was Isaac Newton that came up with the famous formula F=MA. Force equal Mass times Acceleration.
So to reduce the Force, you have to reduce the Mass and the Acceleration.
To reduce the Mass....extensive PED policy with state of the art testing both in NCAA and NFL. Caught one time, out for 2 years just like Olympics. Twice is gone forever.
Acceleration....slow players down. Simple, make them where pads. Not only slows them down, but lessens the hits. Look at players now, knee pads don't exist. Defensive guys don't where thigh pads or hip pads or tailbone pads, some Dlineman barely where shoulder pads. Force every player to where a full set of complete pads that are regulated, so the players don't decide what size, every player essentially wears the same set depending on position and size. This includes rib protection via bodysuit and a full set of pads like you saw back in the 80's. This would greatly reduce injuries seen.
Helmets...probably the #1 thing that needs advancement. Could be done in a heartbeat. Simple to do. NCAA and NFL each put up $10 million to the two main helmet suppliers and say they require a 33% reduction in force of collision in helmets (easily measured with modern technology and they are doing it now) in TWO years. Helmet suppliers would figure it out in no time with some money. Even if the helmets had to get 50% bigger with more padding. Then give another $10 million to 3 Universities and tell them they want a 50-75% reduction in 5-10 years and let some PhD's figure out some new stuff.
Football can be made much safer, but the NCAA and NFL don't want to make is safer as they are concerned it will slow the game down and be less violent. They equate that speed and violence to viewership and viewership is $$$. The NFL owners and NCAA Presidents's and AD's are addicted to the money, it is drug they cannot give up.
Since the V term in the equation is squared, reducing velocity has an exponential impact on reducing the energy in a collision, whereas reducing mass only has a linear impact.