1. HW DueRead 7.1-7.2, Do # 7-10 pg. 100 & Finish POGIL Tonight’s HW Tonight’s HW Read & STUDY 7.1-7.3, Do # 11-13 pg. 100 QUEST Jan 21 st or 23 rd (date TBD) **Since it is an OPEN NOTES QUEST, no study guide or formulas provided. However, study as if it were CLOSED NOTE!!! Do Now 1.Put BOTH of your HW assignments TOGETHER in the In Box (stack them together – don’t need to staple) 2.Reviewing test – sharing answer keys, checking, correcting, and understanding WHY the answer is what it is - - need help? See a teacher or peer you trust!

2. LET’S REVIEW… The following slides contain some key points you should have learned in LAST CLASS’ POGIL You will be going BACK to LAST CLASS’ Do Now (EGG TOSS) in a few minutes to explain what actually happened based on ALL you learned so far, so take those out now…

3. CHANGE in momentum is caused by an IMPULSE Impulse is a Force exerted for a period of time… it is the PRODUCT of force x time Since Impulse equals CHANGE in momentum…. IMPULSE = m Δv = Δ p IMPULSE = force x time J = F. t or Imp = F. t J = Δ p or Imp = Δ p F. t = Δ p or F. t = m Δv

4. Newton’s 2 nd Law is:

5.  Substitute the definition for acceleration:

6. Newton’s 2 nd Law is:  Substitute the definition for acceleration:  Rearrange the parentheses

7. Newton’s 2 nd Law is:  Substitute the definition for acceleration:  Rearrange the parentheses  Substitute the symbol p for momentum

8. Newton’s 2 nd Law is:  Substitute the definition for acceleration:  Rearrange the parentheses  Substitute the symbol p for momentum  Move t to the other side of the equation ; impulse equals change in momentum

9. HERE’S HOW THE UNITS WORK Since Impulse equals CHANGE in momentum…. So … we can substitute in the units like this: But remember…the NEWTON is a unit that is shorthand for… So really, the equation’s units could look like this: And after cancelling out the ‘s’ in the numerator and denominator: F. t = m Δv N. s = kg m s kg m. s = kg m s 2 s kg m. s = kg m s 2 s

10. BASED ON LAST CLASS’ POGIL…. 1.Go back to your Do Now 2.Using ALL key terms you learned (force, stopping time, impulse, change in momentum, mass, change in velocity, etc.) please explain WHY the egg did not break when it hit the sheet:

11. COMPARING THROWING AT THE SHEET VS. THE HYPOTHETICAL WALL (ASSUME I THROW THE EGG WITH THE SAME INITIAL VELOCITY) WALLSHEET Same Change in Momentum (m Δv) Same VALUE of impulse (Ft) (*remember, this is the PRODUCT of force x time) But DIFFERENT forces & stopping times! WALLSHEET F t = m Δv = F t In both case, the egg experiences the same momentum change and the same impulse… But it experiences MORE force in a LESSER TIME when it hits the wall…. And LESS force in MORE TIME when it hits the sheet!

12. IN OTHER WORDS Wall F t Sheet F t Imp m Δv Δp

13. TAKE OUT YOUR HW THAT WAS DUE LAST CLASS - POGIL : PART 4 – MOMENTUM MATH Should have finished for HW… any questions? 1.800 kg m/s 2.360 kg m/s If you got 360,000, *check your units!!!* Use DA to convert 5000g  5 kg first! 3.Zero!!! It is AT REST (if it was not at rest, you would need to use DA to change pounds  kg) 4.Marshmallow: 75 kg m/s Bowling Ball: 40 kg m/s Mallow wins! *Check your units!!!* Use DA to convert 50g marshmallow  0.05 kg first!

14. Rank these cars based on momentum before they hit the brakes: Remember…. m v = p 20,000 kg m s 10,000 kg m s s s 20,000 kg m s 5,000 kg m s F B = C = D A = E Most NEGATIVE Most POSITIVE Look at Car A… m = 1000 kg v = 20 m/s Solve for “p” using mv = p mv = (1000kg)(20 m/s) mv = 20,000 kg m s

15. Rank these cars based on THE IMPULSE needed to stop them Remember…. Ft = m Δv - 20,000 N. s-10,000 N. s -20,000 N. s-5,000 N. s A = E B = C = D F Most NEGATIVE Most POSITIVE Look at Car A… m = 1000 kg Δv = v 2 – v 1 Δv = 0 – 20 m/s Δv = - 20 m/s mΔv = (1000kg)(-20 m/s) mΔv = -20,000 kg m s In other words… -20,000 N s

16. Rank these cars based on THE FORCE needed to stop them Remember…. Ft = m Δv Not enough info to solve! Most NEGATIVE Most POSITIVE Look at Car A… mΔv = Ft -20,000 kg m = Ft s Slight problem…. We don’t know the stopping time! Without ‘t’ we can’t solve for F!

17. TAKE OUT YOUR HW THAT WAS DUE TODAY POGIL : LAST PAGE

18. WHAT?HOW?LIST SOME EXAMPLES? CASE 1 Increase Momentum (usually means velocity increases) Apply the greatest force for the longest time CASE 2 Decrease Momentum (usually means velocity decreases) Minimize forces by increasing stopping time Maximize forces while decreasing stopping time FOLLOW THROUGH in sports Bending knees when jumping Bungee jumping with elastic Running on asphalt Airbags! Head 1 st into brick wall Bungee jumping with rope Run on concrete Pulling slingshot back all the way Moving hand back when catching Moving INTO a punch Karate chop Locked knees when jumping

22. Force x time = Impulse= mass x velocity= Momentum Change There are 2 types of algebra problems, combined into one table. Here are your hints when solving: The 3 rd and 4 th columns are always equal; that is, the impulse is always equal to the momentum change. If any two of the first three columns are known, then the remaining column can be computed. This is true because the impulse=force time. Knowing any two of the last three columns allows us to compute the remaining column. This is true since momentum change = mass velocity change.

23. -40 Force x time = Impulse = Change in Momentum = mass x change in vel.

24. POGIL Do not use your book… READ the boxes on the POGIL. Recall prior info, use your HW, and USE THE BOXES!!! Check in at stop signs. You may ONLY USE the computer or a personal device (iPod, phone, etc.) when the instructions call for it; you may only use the listed site – NOTHING ELSE! Otherwise, computer and group privileges will be revoked for today, and personal devices confiscated. Goal is to FINISH THIS TODAY! Whatever is not finished becomes HW Stopping w/10 minutes left for an exit During this time, individual groups will be conferencing w/ a teacher to review your Newton's Laws Tests.

25. EXIT Take out your textbook HW form the past 2 nights: #1-6 And #7-10 We are popcorning – listen, ask questions, make corrections! HW HW Read & STUDY 7.1-7.3, Do # 11-13 pg. 100 & Finish POGIL from today’s class (up to p.4) QUEST Jan 17 th & 21 st, or 22 nd & 23 rd (date TBD) **Since it is an OPEN NOTES QUEST, no study guide or formulas provided. However, study as if it were CLOSED NOTE!!!