Reminder to self: momentum vs inertia
Explaining concepts to myself so they stick
I often loosely reference the concepts of momentum & inertia in everyday life. Building it and maintaining it. But fundamentally what does this mean?
An object's momentum is defined as the following:
p = mv
where
`m` is the object's mass, and
`v` is the object's velocity (a vector quantity with both magnitude and direction)
Therefore to increase momentum, increase mass or velocity. Conversely to decrease it, reduce mass or velocity, or apply an opposing external force.
So what does it mean to say an individual, a team, or a project has "gained momentum"? It's to say that the entity has increased its mass or velocity. For example an idea that has taken greater hold of your life. A team that has grown in size. An ability to execute with greater focus and speed.
How does an entity "lose momentum"? More distraction and chaos. Attrition in personnel and time. Or an external force that is opposing the entity's motion.
Inertia is defined as the following:
The natural tendency of objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes its velocity to change
Inertia is not typically quantified in an equation, rather it's a property of mass itself.
So, what's the relationship between inertia and momentum? Because objects have inertia, they will maintain constant velocity (and therefore constant momentum) unless acted on by a net external force. Therefore when we talk about building momentum, inertia is the property by which we naturally maintain that momentum.
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