# Momentum

BHS
-> Mr. Stanbrough -> Physics -> Mechanics ->
Momentum -> this page

As I'm sure you suspect, momentum in physics is different from
"momentum" in sports on tv, as in "Yes, Chris, the Bengals really
have momentum on this drive!". However,
physics momentum is related to football momentum in that both
concepts refer to how difficult it will be to stop something.
What makes an object difficult to stop? Its mass,
for one thing. After all, mass measures the inertia
of an object - how much the object resists accelerating.
Certainly, more mass means more momentum - the momentum of an object
is directly proportional to its mass. Twice the mass means twice the
momentum. Momentum is not the same as mass, though. For one thing, an
object that is not moving has **no** momentum, no matter how much
mass it has.

Fast objects are also difficult to stop. Bullets have a very small
mass, but you wouldn't want to try and stop one! More speed
means more momentum - momentum is directly proportional to velocity.
Twice the speed means twice the momentum.

Since the momentum of an object is directly proportional to both
its mass and its velocity,

Momentum = (mass)(velocity) = mv

Momentum is a vector quantity. Its direction is the same as the
direction of the object's velocity.

##

Calculating Momentum

Calculating the momentum of an object is usually easy and
straightforward, just multiply the object's mass times its
velocity.

### Example:

A ball of mass 2 kg. is moving with a speed of 4 m/s. What is its
momentum?

### Solution:

Momentum
= (mass)(velocity) = (2 kg)(4 m/s) = 8 kg m/s

BHS -> Mr. Stanbrough -> Physics -> Mechanics -> Momentum -> this page

last update December 27, 2005 by JLStanbrough