Momentum is a measure of how hard it is to stop a moving object; it is the product of the object's mass and its velocity; since velocity is a vector, momentum is a vector
Quantity. The symbol for
momentum is p and SI units are either N sec or kg m/sec. The direction of the
momentum is the same as that of the velocity.
p= m v
where p is momentum, m is mass in kg, and v is velocity in m/s
High mass objects can have low momentum when they have low velocities; low
mass objects can have high momentum when they have high velocities. The more
momentum an object has, the harder it is to stop.
How can we relate momentum and force? The
rate of momentum of a body is proportional to the net force applied to it.
Conservation of Momentum.
In the absence of outside forces, the total momentum of a set of objects remains the same no matter how the objects interact with one another.
Lets examine the three possibilities shown in the picture above.
In the first case, a small mass hits a large mass.
Think about me hitting Tony Boselli.
The second case is familiar to those who play pool.
In the second case, the masses are the same.
The third case shows a large mass hitting a small mass.
Try the applet at this web site for experimentation. Note they use an air track so friction can be ignored.