Momentum Facts

Momentum is a term that describes the strength of a moving object. Objects that are not moving, do not have any momentum. Things that are moving have less momentum if they are lightweight or moving slowly and the opposite is true if they are moving fast or are heavy. An example of this might be tested at a bowling alley. Imagine trying to knock the pins down with a ping pong ball. The ball is too light, even if it is going fast. The bowling ball is heavier and has more momentum.

A way to think about momentum is to consider how difficult it would be to stop an object in motion. An object that is bigger or going faster can be said to have momentum equal to mass x speed (velocity). An example of this would be to compare how difficult it would be to stop a car that is going 35 mph. The mass of the car would be difficult to stop, even if it were going slower. If you hit a baseball, even though it is smaller, the speed that it is going is faster, and it is a bit difficult to stop it. It takes longer to stop a car than it does a baseball.

  • In physics, the formula is momentum = mass x velocity. The word momentum is actually expressed using the letter ‘p’, so the formula is p = m * v.
  • Momentum can be measured and is usually done as kilograms x meters per second (kg*m/s). They are also measured in newton-seconds (n’s), named after the famous scientist, Isaac Newton.

Velocity is considered to be a ‘vector’ and so momentum is also a vector. What this means is that in addition to the value of the momentum, it also has a direction and the momentum direction is expressed by an arrow or ‘vector’.

  • Certain objects, such as planets or stars, have momentum in space that allow them to continue to go in the same direction unless something comes along to push in another direction or stop it all together.
  • In our Milky Way galaxy, the sun continues to go around and the earth continues to go around the sun. On earth, we have friction with the air or water that gradually pushes an object to make it slow down or stop.

’Angular momentum’ is when an object spins around, as in a top, instead of proceeding in a straight line such as a car or baseball. The bigger and faster things are more difficult to stop or change direction than lighter or slower things.

In space we see angular momentum in the stars, planets, nebulae and even black holes. They all spin and without anything to change it, will continue to spin.

In the ‘law of conservation’ it states that you cannot lose momentum, it always has to go somewhere. Examples might be a snowball rolling down a hill. The snowball gains more momentum. You have seen momentum when an ice skater increases their momentum in spinning. They start out with their leg extended, spinning around and as they bring their leg closer to their body, the spin increases to a faster pace. They are gaining momentum.

Wind can also create momentum in the development of a tornado or a hurricane.


Momentum conversation is an important aspect of physics. It basically is the law that describes the resulting situation of two items that crash into each other. It states that when two items collide the results are the combination of the momentum of each of the objects. The objects themselves may be reduced in momentum, but the results are combined.