Group: Max, Shulan, and Miuki

• When a sport coach tells his team that they have a lot of “momentum”, he means that the team is difficult to stop.

• In physics, “momentum” can be defined as “mass in motion”.

• In other words, momentum is how much “stuff” (mass) is moving and its velocity.

• The equation for momentum is•  P = mv

o Where m is the mass of the object and v is the velocity of the object.

o To prove in units: [kg][m/s]=[kg*m/s] or [N*s]

• Momentum is a VECTOR quantity.

• In the momentum equation, velocity is involved, so that means that momentum

has a magnitude and a direction. (P = mv)

• Momentum is CONSERVED in a system.

• This means that the amount of momentum that is present in the system before is always equal to the momentum after.

•pbefore = pafter

• In an elastic collision, the two objects that collide bounce off of each other.

• The equation for an elastic collision has to conserve momentum because momentum is always conserved.

• pbefore = pafter

• P = mv

•m1v1 + m2v2 = m1’v1’ + m2’v2’

• In an inelastic collision, the two objects crash into each other but they do not bounce apart.

• Momentum is still conserved but the equation has changed because the two objects are stuck together after collision.

• pbefore = pafter

• P = mv• m1v1 + m2v2 = v(m1+m2)

Impulse 

An impulse is when a force is exerted onan object on a period of time causing achange in momentum.• ∆p=F∆t

Impulse is also equal to:m∆v=F∆t

This is because change in momentumequals m*v

SI unit of Impulse 

The SI unit of an impulse is the same asthe SI unit for momentum, which is whythe two equations can be related.• F∆t= ∆p• [N]*[s]=[N*s]

Compare this to momentum• [kg]*[m/s]=[N*s]



Holt Textbook

pg 209/ 6A.2 

pg 211/ 6B.4

pg 219/ 6D.1