1. Explosions

2. Explosion means separation
Explosion means separation. Two things which are initially together and they separate.

3. Example 1 : gun and bullet.

4. What is the total initial momentum?
p = mv
p = 0kgm/s since both the gun and the bullet are initially at rest.
What is the total final momentum? p = 0kgm/s
What is the velocity of the rifle?
0 = 6 x v x 1100
0 = 6v + 55
--55 = 6v v = m/s ( negative means moving in the opposite direction)
This kind of velocity is called RECOIL VELOCITY.

5. A girl of mass 40kg jumps out of a stationary boat of mass 200kg with a velocity of 1.5m/s.
What is the total initial momentum?
p = mv, p = 0kgm/s
What is the total final momentum? p = 0kgm/s
With what speed will the boat recoil?
p = mv
0 = 40 x x v
O = v
-60 = 200v v = - 0.3m/s ( negative means moving in the opp direction)

6. Lisa is standing opposite Angie. They both have an equal mass
Lisa is standing opposite Angie. They both have an equal mass. They push each other away. What can you say about their velocities ?
Since they are both stationary at the beginning, their total initial momentum is 0kgm/s.
Their final momentum will also be 0kgm/s.
When they push each other away…….
p = mv
0 = mv + mv
-mv = mv
-v = v their velocities are equal and opposite.

7. A toy rocket of mass 5kg shoots up with a velocity of 4m/s
A toy rocket of mass 5kg shoots up with a velocity of 4m/s. The gas flows out in the other direction with a velocity of -100m/s.
What is the total initial momentum?
p = mv
p = 0kgm/s since both the rocket and gas are initially stationary.
What is the total final momentum? p = 0kgm/s
What is the mass of the gas?
0 = 5 x 4 + m x -100
0 = 20 – 100m
100m = m = 0.2kg