Lesson about Momentum and Impulse

1. Ms. Beverly Rom

2. Momentum is what Newton called
the “quantity of motion” of an object.

3. The momentum of an object:
Depends on the object’s mass.
Momentum is directly proportional to mass.
Depends on the object’s velocity.
Momentum is directly proportional to
velocity.

4. In symbols:
p = mv
p
m v

5. Momentum is a vector quantity.
Common units of momentum: kg m/s

6. Determine the momentum of:
A 110-kg professional fullback running
across the line at 9.2 m/s.
A 360,000-kg passenger plane taxiing
down a runway at 1.5 m/s

7. A 110-kg professional fullback running across
the line at 9.2 m/s.

8. A 360,000-kg passenger plane taxiing
down a runway at 1.5 m/s

9. The impulse exerted on an object
depends on:
The force acting on the object.
Impulse is directly proportional to force.
The time that the force acts.
Impulse is directly proportional to time.

10. In symbols:
I = Ft
I
F t

11. Impulse is a vector quantity.
Common units of impulse: N s

12. The impulse exerted on an object
equals the object’s change in
momentum.

13. In symbols:
I = Dp

14. Find the impulse and force which
make 12m/s change in the velocity of
object having 16kg mass in 4 s.

15. Since impulse = change in momentum,
If no impulse is exerted on an object, the
momentum of the object will not change.

16. If no external forces act on a system, the
total momentum of the system will not
change.
Such a system is called an “isolated system”.

17. Momentum is conserved in every
isolated system.

18. Another way to think about it is:
Internal forces can never change
the total momentum of a system.

19. In practice, for any event in an
isolated system:
Momentumafter = Momentumbefore