1. Impulse & Momentum 1

2. Think About It!
Is a pin more likely to move rapidly when a bowling ball travels toward it at a high speed or at a low speed?

3. What if you had two bowling balls of different masses move at the same speed, which is more likely to move the pin?
Let’s Ask Bill Nye!

4. Why do falling hailstones have the capacity to damage cars and buildings?

5. Momentum
Is it harder to stop the Titanic or a rubber ducky if they are traveling at the same speed?
We say that Titanic has more MOMENTUM than the rubber ducky.
Momentum is inertia in motion.

6. Momentum:
the product of an object’s mass and velocity.
p = mv
Vector

7. How is momentum calculated?
Formula p = m x v
Units kg m/s = kg x m/s
Abbreviations p = momentum
m = mass (kg)
v = velocity (m/s) 7

8. Impulse

9. Impulse
The result of force acting on an object for a specific time.
Impulse (J):
J = FΔt
Units: Newton Seconds (N s)
Vector

10. Impulse-Momentum Theorem
Impulse is the area under a Force vs. Time Graph

11. Impulse-Momentum The greater the force, the greater the acceleration.
Therefore, there is a greater change in velocity, and a greater change in momentum.

12. F = ma = m v t = m v p F t m v = p Impulse = change in momentum
(Newton’s Second Law)
= m v t =
m v p
F t
m v = p
Impulse = change in momentum

13. 30,000 N of force acting for 1.0 s (a crash!)
A 1000 kg car moving at 30 m/s
(p = 30,000 kg*m/s)
can be stopped by
30,000 N of force acting for 1.0 s (a crash!) or
by 3000 N of force acting for 10.0 s
(normal stop)

14. Impulse-Momentum Theorem
Impulse = change in momentum can be written as:
J = Δp OR
F Δ t = mΔv
Impulse is Ft. We just saw on the first slide. Momentum is mv. The triangle just means the change.

15. MOMENTUM Ft Decreasing Momentum:
Which would it be more safe to hit in a car ? Ft mv mv Ft

16. MOMENTUM
In each case, the momentum is decreased by the same amount or impulse (force x time)
Hitting the haystack extends the impact time (the time in which the momentum is brought to zero).
The longer impact time reduces the force of impact and decreases the deceleration.
Whenever it is desired to decrease the force of impact, extend the time of impact !

18. Why have most cars had metal bumpers replaced with plastic ones?18

19. Other improvements made by the department of transportation19

20. Impulse-Momentum Theorem-Football
Football Collisions

21. Why is a catcher’s mitt different?21

23. “Roll with the punches”23

24. Parkour! (How to survive a landing)
Advanced Rolling
Decrease the change in momentum
Increasing the time of contact decreases the force. 24