Momentum is generally used to mean increasing forward motion. A boulder rolling down a hill gains momentum. So does a great idea, a team on a winning streak, or the economy.

To find an object's physical momentum you multiply its mass by its velocity. Determining the momentum of the economy or the latest fad is much more difficult. Used figuratively, momentum implies that, like a boulder rolling down a hill, something with momentum will continue moving forward on its own. If you're running for class president, you might want to build momentum by holding a few rallies, passing out flyers and starting a website. Once you have momentum, your opponents won't be able to stop you.

Definitions of momentum

n the product of a body's mass and its velocity

“the momentum of the particles was deduced from meteoritic velocities”
angular momentum
the product of the momentum of a rotating body and its distance from the axis of rotation
Type of:
physical property
any property used to characterize matter and energy and their interactions

n an impelling force or strength

“the car's momentum carried it off the road”
Type of:
force, forcefulness, strength
physical energy or intensity

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