  Momentum

I. Momentum - the property of a moving object that makes it difficult to stop. "Which is tougher to stop, a bowling ball or  a baseball?"  It Depends .... If the baseball had a much larger velocity, it  would be harder to stop.

(technically, product of mass and velocity) Momentum = Mass x Velocity

p = mv

(kgm/s)  (kg)(m/s)

a) vector quantity

b) p has same direction as velocity

c) units - kgm/s

Momentum helps us
understand collisions

[Flash]

Kinetic Energy is conserved in perfectly elastic collisions

 Perfectly Elastic Collision?

No

The ball's energy is lost in the collision with the floor. It does not return its original position. "Could a moving baseball have the same momentum as moving bowling ball?"   "Yes. p = mv. The baseball's velocity would have to be many  times faster."

1) Relationship between force and momentum

When a force acts on a body it
changes its' momentum.

Mathematical Relationship, F, p

p = mv

so ...

Δp = mΔv

Fnet = ma

so ...

 Fnet = m Δv t

(Cross Multiply)

Fnett = mΔv

Since ...

Δp = mΔv

Then ...

Fnett = Δp

Force is the time rate
of change in momentum

 Fnet = Δp t

Δp = Ft   The change in momentum that an unbalanced force produces on an object depends on .... ... how long the force acts on a body.  "Could a female golfer EVER change the momentum of a golf ball more than a male golfer?" Yes. She can compensate for a smaller force
by employing a good 'follow through'

2)  Impulse

 J = Fnett (Ns) or (kg•m/s)

Combining all the equations

 * J = Fnett = mΔv =Δp *

Given this equation, what is another unit for momentum besides kgm/s?

 * J = Fnett = mΔv =Δp *

Ns  