1. Momentum
Contents:
New concept
Example
Whiteboards

2. = “Keep Goingness” of an object.
p = mv where
p = momentum
m = mass in kg
v = velocity in m/s
Momentum

3. They can stop dead.
i.e. mv = mv
So if a fast moving little object collides with a slow moving big object head on

4. Example: What is the momentum of a 145 g baseball going 40. m/s?
p = mv = (0.145 kg)(40. m/s)
p = 5.8 kgm/s

5. Whiteboards
Momentum
1 | 2 | 3 | 4

6. What is the momentum of a 0.0210 kg swallow going 5.20 m/s
kgm/s
p = mv
p = (0.021 kg )(5.2 m/s) = kgm/s
African W

7. What velocity must a 0. 0082 Kg bullet have for its momentum to be 5
What velocity must a Kg bullet have for its momentum to be 5.8 kgm/s
707 m/s
p = mv
5.8 kgm/s = (0.0082kg)v
v = (5.8 kgm/s)/(0.0082kg) = 707 m/s W

8. A bowling ball has a momentum of 43. 6 kgm/s when it is going 12 m/s
A bowling ball has a momentum of 43.6 kgm/s when it is going 12 m/s. What is its mass?
3.6 kg
p = mv
43.6 kgm/s = m(12 m/s)
m = (43.6 kgm/s)/ (12 m/s) = 3.6 kg W

9. The momenta must be equal but opposite:
60 kg Fran is running at 4 m/s when she collides with 80 kg Joe. They hit and stop dead, so how fast was Joe going?
3 m/s
The momenta must be equal but opposite:
Fran: p=mv=(60 kg)(4 m/s)=240 kgm/s
Joe: p=mv, 240 kgm/s = (80 kg)v,
v = (240 kgm/s)/ (80 kg) = 3 m/s. W

10. Consider the previous problem:
Since momentum is really a vector, the true initial momenta were:
Fran: p=mv=(60 kg)(+4 m/s)=+240 kgm/s
Joe: p=mv=(80 kg)(-3 m/s)=-240 kgm/s
The total momentum was the same before and after the collision.
This is true for every collision.
This is very useful