Wednesday, November 23, 2011

Gaming: Mass x Velocity = Momentum

Momentum can be defined as "mass in motion." All objects have mass; so if an object is moving, then it has momentum - it has its mass in motion. The amount of momentum that an object has is dependent upon two variables: how much stuff is moving and how fast the stuff is moving. Momentum depends upon the variables mass and velocity. In terms of an equation, the momentum of an object is equal to the mass of the object times the velocity of the object.

 From the definition of momentum, it becomes obvious that an object has a large momentum if either its mass or its velocity is large. Both variables are of equal importance in determining the momentum of an object. Consider a Mack truck and a roller skate moving down the street at the same speed. The considerably greater mass of the Mack truck gives it a considerably greater momentum. Yet if the Mack truck were at rest, then the momentum of the least massive roller skate would be the greatest. The momentum of any object that is at rest is 0. Objects at rest do not have momentum - they do not have any "mass in motion." Both variables - mass and velocity - are important in comparing the momentum of two objects.

Now the obvious question becomes, ‘and then what?’ What momentum helps us understand is whether or not a unit can realistically accomplish the task we are setting it out to do. Is the unit fast enough and large enough to complete its mission without being destroyed beforehand? Let take two examples, a 6 man Space Wolf squad in a razorback versus a 10 man Space Wolf squad in a rhino. Both can move 12 inches so their velocity is the same, however the size of the 10 man squad represents a 66% increase in mass over the 6 man squad.

What’s the point? The point is that a 10 man squad will have a 66% increase in momentum over a 6 man squad. (for those of you who are saying, ‘no – it’s a 40% increase. stupid tallarn.’ remember that we are using 6 as the base unit of measure not 10, so 4 additional Marines represents a 66% increase over 6 marines.) Well durr, we all know that, It’s simple math!

Of course you do. However, do you understand what momentum feeds directly into? Tempo - tempo is dictated by momentum as momentum creates tempo. Without sufficient momentum it is impossible to create or even dictate tempo.

Tempo is the competitive rhythm that will develop between the opposing armies with each player trying to influence and exploit tempo and the continuous flow of events to suit his purposes. Success by maneuver, which is most commonly employed by Space Marines, is often disproportionate to the effort made. A simple example of success by maneuver would be a unit of Space Wolf Scouts assaulting from the opposing players board edge into a heavy weapon squad, the cheaper unit will earn much more than its own points cost back and cause significant disruption to the enemy plan. The chance of failure becomes higher for the scouts if the enemy has prepared for their arrival and the points are essentially wasted. Thus our potential for success or failure, and the costs of both, is disproportionally higher for forces relying on maneuver than attrition.

Ok, so now im confused. Mass, Velocity, Momentum and Tempo – what in the hell are you getting at!

The point is the absolute necessity to accurately evaluate the units you assign to complete a task and make sure that you have enough forces to complete the task. You want to be able to force your opponent to react to you, not the other way around. If you send 6 Grey Hunters in a Razorback to seize an objective across the board, chances are they won’t make it. However, if you leave the Razorback and 6 Marines to defend the objective in your deployment area while dispatching two Rhino’s full of Grey Hunters to go get that same objective you will probably be successful. Not only that, but you will more than likely disrupt the enemy plan enough that they will be repositioning their forces in reaction to your move against their objective instead of moving to take yours. This forces your opponent to react to you and allow you to seize the tempo in your favor.

clearly a proponent of controlling tempo and other things!
As is the case with most tactics articles most people will react with something like ‘well, durr – we all know that already’ but the point is sometimes to simply remind us of what we already know, but might not always practice.

still practicing_



  1. I object to your use of antiquated Newtonian physics. I expect a post using quantum mechanics and/or general relativity as a metaphor for tactics and strategy. Post Haste!

    In all seriousness, the counter argument to this for an MSU unit is that while the smaller unit has less mass, it also has the advantage of location and duplication. It may take more force to adjust the momentum on the larger squad, it will in general take more applications of force to change the momentum of equivilent points of MSU units. There is also the sequential realtity of 40k where we pick one unit and resolve its shooting before moving on to the next -- at least for shooting. In your case, your wolves are designed to be in assault and in that case MSU is at a disadvantage in 5ed.

    What's more, the devs have tried to create advantages within unit selection that favor larger units. Tactical squads are the most obvious (and also the most amaturish) example of this. I think things like flat rates for Wolf banners, psybolts and rules that affect whole units like catalyst help push a player toward the larger units. But that is a topic for another day.

  2. I do agree to a point about large units and you are right, GW does have some interesting ways of pushing us towards larger units which is indeed a topic for another day...

    However, multiple small units create more opportunities for the enemy to disrupt squads and create friction. Friction saps momentum and slows our tempo. Lower model counts mean more frequent leadership checks and reduced efficiency.

    In 40k points costs mean that most games will be fought on an 'equal footing' so our concept of battle must rely on being able to impose our will upon the enemy and force him to react to us. This requires that we have redundancy and survivability built into our lists so that disruption of our plan becomes more problematic.

    Another wrinkle is terrain on the battlefield and the reduced maneuver room for vehicles in response to the overuse of 'mech guard' that occurred in the last two years. Tournament organizers both here and in Europe are increasingly using terrain as a way to bottle up transports and remove some of the mech advantage...

    I think you just gave me enough ideas for two more articles!