1. Things you wanted to know, but were afraid to ask.
IMPULSE AND MOMENTUM
Things you wanted to know, but were afraid to ask.

2. I. IMPULSE A baseball hits a bat.
The velocity of the bat changed. (Vf-Vi)
The velocity of the ball changed. (Vf-Vi) Vi Vi Vf Vf

3. B. NEWTON’S 3rd Law
For every action (ball hitting bat), there is an equal and opposite reaction (bat hitting ball).
FORCE IS THE SAME ON BOTH OBJECTS!
BUT : the velocities of the two objects are completely different.
WHY?

4. F∆t=m∆v C. NEWTON’S 2nd LAW He took his formula F=ma:
Changed it to F = m *(∆v/∆t)
Put ∆t on the other side to get the formula:
Affectionately called fatmav.
NEWTON CALLED F∆t, Impulse
So I = F∆t
F∆t=m∆v

5. II. Momentum A Car and a bus are both going 30 m/s.
Which one has more Force?
Neither, the force on both is zero
Which one does more damage?
The bus, but why? V V

6. B. Momentum
The bus has more of something, and it is called momentum.
Newton named it and wrote the formula:
p = mv

7. III. IMPULSE MOMENTUM THEOREM
I = F∆t
p= mv
F∆t = m∆v
Therefore:
Impulse momentum theorem is that the impulse on an object is equal to the change in momentum of that object.
I = ∆p

8. IV. Law of conservation of Momentum
We are talking about collisions here!
The total momentum of all the objects before a collision must equal the total momentum of the objects after the collision.
Assuming no energy lost (elastic collision)
Reality (inelastic collision)
Pbefore = Pafter

9. EXAMPLE
A rifle with a mass of 5 kg fires a bullet with mass of 3 g at a velocity of 700 m/s. What is the recoil velocity of the rifle?
m1v1 = m2v2