1. Momentum & Impulse
Seo
Physics

2. Objectives To understand how impact is given onto an object(s)
To find the relationship between Force, mass, velocity and time
To introduce conservation theory

3. Arresto Momentum !! (kg* m/s = kg * m/s) What is Momentum?
The amount of motion created with Object’s certain mass and velocity
Momentum is denoted in small letter p
(Units in kg*m/s)
Equation?
p= m*v ; (Momentum = mass * velocity)
(kg* m/s = kg * m/s)
Vector quantity
Both magnitude and direction

4. Practice What is the momentum of a fly that is
10 grams and flies at 2 m/s?
10g=.01kg
p=m*v=.01x2= (0.02kg*m/s)
What is the momentum of a turtle that is 1kg and moves at .05m/s?
p=m*v=1x.05= (0.05kg*m/s)
The turtle has more momentum
(larger magnitude).

5. DIY
What is the momentum of a truck that is 2500 kg and speeds at 9 m/s?
p=m*v=2500 kg * 9 m/s
22,500kg*m/s
What is the momentum of a bulldozer that has a mass of 3210kg and moves at 7m/s?
p=m*v=3210 kg * 7 m/s
22,470kg*m/s

6. Net Momentum What is Net Momentum? Sum of all momentum in an object
Exists in 1D and 2D momentum
Ex). What’s the total momentum of Object 1
and Object 2?
pobject1 = (0.83kg*m/s, Left)
Pobject2 = (0.32kg*m/s, Left)
Momentum is a vector so we need to do vector addition
pnet = Σp = p1 + p2 + …
pnet = 1.15kg* m/s, Left

7. Momentum Crash

8. Impulse What is Impulse? Units? 1) J= F*t (Impulse = Force *time)
1) Change in Momentum
2) Impact caused by force and amount of time in an object
Denoted as upper-case J
Equations?
1) J= F*t (Impulse = Force *time)
2) Δp = mΔv
Units?
Newton-Seconds or N*s

9. J = m*(vfinal – vinitial)‏ J = 5 kg*(3m/s-5m/s)=-10kg*m/s
Impulse Practice
A bowling ball (5kg) moving at 5m/s bowls through a set of bowling pins. Right before the ball falls down the shoot it is going 3m/s
What is the impulse the bowling pins provide to a bowling ball?
J = mΔv
J = m*(vfinal – vinitial)‏
J = 5 kg*(3m/s-5m/s)=-10kg*m/s

10. J = mΔv = m*(vfinal-vinitial) = .3*(25-0) = 7.5kg*m/s J = FΔt
DIY
In football, a field goal is kicked with the football initially at rest. The football 0.3 kg is kicked at 25m/s.  The player's foot was in contact with the ball for 0.1 seconds.
What was the impulse on the ball?
What is the average force during the time of contact?
J = mΔv = m*(vfinal-vinitial) = .3*(25-0) = 7.5kg*m/s
J = FΔt
7.5 = F * 0.1
F= 75 N

11. Impulse

12. Impulse-Momentum Theorem

13. Conservation of Momentum
What does it mean to be Conserved?
Matter is neither lost nor destroyed; transferred fully
What is Conservation of Momentum?
Equation?

14. What is an Elastic Collision?
Collision that does not stick and repels
Ex) Spring stretches then coils back
Equation?
m1iv1i+ m2iv2i=m1fv1f+ m2fv2f

15. Inelastic Collision What is an Inelastic Collision? Equation?
Collision that sticks and attracts
Partially Inelastic Collison
Separated but not in original form
Perfectly Inelastic Collision
When two objects collide and stick together
Equation?
m1iv1i+ m2iv2i=vf (m1+m2)
Ex. In Biology, combination
of Nucleotides and form a
double helix

16. Practice
A 10 kg object moves at a constant velocity 2 m/s to the right and collides with a 6 kg object moving at a velocity 5 m/s to the left.
What are the initial and final momentum of the system?
mr = 10kg, vr = 2m/s, ml = 6kg, vl = -5m/s,
p = mv
pi = m1v1i + m2v2i
pi = 10*2 + 6*(-5) = -10kgm/s = (10kgm/s,left)

17. DIY p = mv m1v1i + m2v2i = m1v1f + m2v2f
Car A with a mass of 24,000 kg moves at a constant velocity of 8 m/s collides with an empty stationary car B with a mass of 10,000 kg. After the collision the car A is moving at 5 m/s in the same direction. What is the velocity of car B after the collision?
m1 = 24,000kg
v1i = 8m/s
v1f = 5m/s
m2 = 10,000kg
v2i = 0m/s
v2f = ?
p = mv
m1v1i + m2v2i = m1v1f + m2v2f
24,000*8 + 10,000*0 = 24,000*5 + 10,000*v2f
v2f = 7.2 m/s

18. TOT Bar Charts Representational tool to visualize initial
momentum, Impulse/system, and final momentum
Initial momentum
Final momentum

19. TOT Bar Charts Practice
A 8kg cart 1 moving with 10m/s to the right strikes a 10kg cart 2 that starts with 2 m/s. If the 10kg cart 2 is moving with 6m/s to the right after the collision, what is the velocity of the 8kg cart after the collision?
Equation: m1v1i + m2v2i = m1v1f + m2v2f
m1v1i=(8 kg*10 m/s)=80 kg*m/s m2v2i=(10 kg*2 m/s)=20 kg*m/s
m1v1f=(8 kg*vf) m2v2f=(10 kg*6 m/s)=60 kg*m/s
80 kg* m/s + 20 kg* m/s = 8 kg* v + 60 kg* m/s v= 5 m/s
Initial momentum
Final momentum