The document discusses the principle of conservation of momentum. It states that in an isolated system, the total momentum before and after a collision or interaction between objects will remain the same. It provides examples of elastic collisions, where objects move separately after collision with the total momentum conserved, and inelastic collisions, where objects stick together with the total momentum but not necessarily the total kinetic energy conserved. Applications to real-life examples like billiards, cars colliding, and projectiles are presented. Worked examples calculate velocities before and after collisions.

1. Principle Of Conservation Of
Momentum
In the absence of an external
force, the total momentum of a
system remains unchanged.

2. •In any collision or interaction between two or
more objects in an isolated system , the total
momentum of the system will remain constant
•that is the total momentum before collision will be
equal to the total momentum after the collision

4. ELASTIC
After two objects moving with their
respective velocities do collide, those
two objects will move separately.
The total momentum = The total
before collision momentum after
collision
22112211 vmvmumum

5. Elastic collision

6. 6

7. A trolley of mass trolley 3 kg and moving with a velocity
0.6 ms-1 and collides with a stationary trolley with a mass
2 kg . After collision the trolley of mass 3 kg and moving
with a velocity 0.2 ms-1. What is the velocity of the trolley
of mass 2 kg after collision?

8. 1
1
1
1
1
2.0
6.0
3
msv
msu
kgm
))(2()2.0)(3()0)(2()6.0)(3( 2v
22112211 vmvmumum
226.008.1 v
6.08.12 2v
?
0
2
2
2
2
v
u
kgm
6.0
2
2.1
2v
Velocity of
trolley, 2 kg

9. INELASTIC
After two objects moving with their respective
velocities do collide, they stick together and move
with a common velocity
Based on The Principle Of Conservation Of Momentum,
The total momentum = The total momentum
before collision after collision
vmmumum 212211

12. A trolley of mass 1 kg and moving with a velocity of 6 ms-1
collides with a stationary trolley with a mass 3 kg . After
collision they stick together with a common velocity. What is
their common velocity?

13. 1
1
1
6
1
msu
kgm
0
3
2
2
u
kgm
vmmumum 212211
))(31()0)(3()6)(1( v
v406
5.1
4
6
vCommon
velocity

14. Similarities
and
Differences
differences
Elastic collision
Total amount of
kinetic energy is
conserved
Inelastic
collision
Total amount of
kinetic energy is
not conserved
Similarities
Total
momentum is
conserved
Total energy is
conserved
Total mass is
conserved

15. Application in real life:
•Kicking football
•Water hose
•Rifle
•Playing bowling

16. Diagram below shows object X and object Y before and after
an inelastic collision. The mass of object X and object Y are 5
kg and 1 kg respectively. What is the velocity, v of both object
after collision, in m s–1?

17. Car A Car B
Car A of mass 100 kg traveling at 30 m s-1 collides with
Car B of mass 90 kg traveling at 20 m s-1 in front of it.
Car A and B move separately after collision. If Car A is
still moving at 25 m s-1 after collision, determine the
velocity of Car B after collision.

18. Car A of mass 100 kg traveling at 30 m s-1 collides
with Car B of mass 90 kg traveling at 20 m s-1 in
front of it. Car A is pulled by Car B after collision.
Determine the common velocity of Car A and B
after collision.

19. A bullet of mass 2 g is shot from a gun of
mass 1 kg with a velocity of 150 m s-1 .
Calculate the velocity of the recoil of the gun
after firing.

20. An arrow of mass 150 g is shot into a wooden
block of mass 450 g lying at rest on a smooth
surface. At the moment of impact, the arrow is
travelling horizontally at 15 ms-1. Calculate the
common velocity after the impact.