**Momentum **

The sports announcer says, “Going into the all-star break, the Chicago White Sox have themomentum.” The headlines declare “Chicago Bulls Gaining Momentum.” The coach *pumps* up his team at half-time, saying “You have the momentum; the critical need is that you use thatmomentum and bury them in this third quarter.”

**Momentum** is a commonly used term in sports. A team that has the momentum is on*the move* and is going to take some effort to stop. A team that has a lot of momentum is really *on the move* and is going to be*hard** to stop*. Momentum is a physics term; it refers to the quantity of motion that an object has. A sports team that is *on the move* has the momentum. If an object is in motion (*on the move*) then it has 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.

**Momentum = mass • velocity**

In physics, the symbol for the quantity momentum is the lower case **p**. Thus, the above equation can be rewritten as

**p = m • v**

where **m** is the mass and **v** is the velocity. The equation illustrates that momentum is directly proportional to an object’s mass and directly proportional to the object’s velocity.

The units for momentum would be mass units times velocity units. The standard metric unit of momentum is the kg•m/s. While the kg•m/s is the standard metric unit of momentum, there are a variety of other units that are acceptable (though not conventional) units of momentum. Examples include kg•mi/hr, kg•km/hr, and g•cm/s. In each of these examples, a mass unit is multiplied by a velocity unit to provide a momentum unit. This is consistent with the equation for momentum.