1. Conservation of momentum

2. Scenario 1

3. Scenario 2

4. Scenario 3

5. positive
ball A
ball B
mass = 2 kg
mass = 3 kg
initial velocity = 3 ms-1
initial velocity = 0 ms-1
initial momentum =
6 Ns
initial momentum =
0 Ns
final velocity = 1 ms-1
final velocity = ?
final momentum =
2 Ns
final momentum =
3v Ns
impulse on A =
impulse on B =
change in momentum
= 2x1 – 2x3
= -4 ms-1
change in momentum
= 3v - 0
The Impulse on ball A is equal in magnitude to the Impulse on ball B but in the opposite direction
4 = 3v
v = 4/3 ms-1

6. positive
ball B
ball A
mass = m1
mass = m2
initial velocity = u1
initial velocity = u2
final velocity = v1
final velocity = v2
I1 = m1v1-m1u1
I2 = m2v2-m2u2
The Impulse on ball A is equal in magnitude to the Impulse on ball B but in the opposite direction
I1 = -I2
m1v1-m1u1 = -(m2v2-m2u2)
m1v1-m1u1 = -m2v2+m2u2
m1v1+m2v2 = m1u1+m2u2
The total momentum before impact = the total momentum after impact