1. Helmets and Force!
October 2, 2014

2. 60 Seconds of Breathing!

3. BELL RINGER!
Predict:
What is the major role of helmets and why is it important for people to wear them?

4. Think…
Write down at least three times when you have worn a helmet or when someone would wear a helmet!

5. Write down this equation:
F: Force
m: Mass
a: Acceleration
What is a force?
PUSH OR
PULL!

6. Newton’s 2nd Law!
Acceleration of an object is proportional to the net force.
Acceleration of an object is inversely proportional to the mass.
More Force= Greater Acceleration
More Mass= Smaller Acceleration

7. Which One?
If you had a choice between hitting a brick wall or a large stack of hay which one would you rather hit?
Why?

8. Stack of Hay
* The longer the time, the smaller the deceleration is, resulting in a SMALLER FORCE!

9. Brick Wall

10. Think…
Imagine a linebacker who has a mass of 109kg who hits a fullback at a deceleration rate of -41m/s2. What is the force or impact on the linebacker’s helmet at time of collision? (Hint should be in units of N).

11. Head Injuries
More than 60% of bicycle-related deaths are from head injuries.
88% of theses injuries could be prevented by wearing helmets (according to Bicycle Helmet Safety Institute)!
Helmets should be replaced every 3-5 years.

12. Helmets Helmets mainly protect against skull and brain injuries!
Everyday biomechanical engineers are working on improving helmets in order to improve their protection.

13. Concussions
Predict:
Why do helmets not do a very good job with protecting against concussions???

14. BRAIN Helmets mainly protect the skull but not the brain
Your brain weighs ~ 2-3 pounds
Quite soft and floating in special water called: cerebrospinal fluid (provides nutrients to the brain)
When a person hits their head hard enough, the brain hits the skull, causing the brain to be bruised and can damage the nerves = CONCUSSION (temporary loss of normal brain functioning)!

15. Brain V. Egg
Think:
What is the brain like in an egg? V.

16. Brain V. Egg The brain is like the YOLK in the egg!
Even though you can keep the egg from cracking, the yolk keeps moving and hitting the shell, just like the brain hitting the skull!
Scientists work every day to solve this problem and reduce the amount of concussions!

17. THINK!
What have you done or what can you do to your helmet in order to keep your egg from cracking and protect from injury?
Write down thoughts in composition notebook.