HW Due Place both in In Box (POGIL & 14-17)

HW Complete #1-16 on today’s packet

Do Now

1.Take one and complete BOTH SIDES.

May work with peers.

A bug and the windshield of a fast moving car collide. Tell whether the following statements are true or false, and EXPLAIN your reasoning:

a. The forces of impact on the bug and on the car are the same size.

1. True2. False3. Not enough info4. Not quite sure

TRUE!FORCES COME IN PAIRS!

A bug and the windshield of a fast moving car collide. Tell whether the following statements are true or false, and EXPLAIN your reasoning:

b. The impulses on the bug and on the car are the same size.

1. True2. False3. Not enough info4. Not quite sure

TRUE!SAME FORCE, SAME CONTACT TIME

A bug and the windshield of a fast moving car collide. Tell whether the following statements are true or false, and EXPLAIN your reasoning:

c. The changes in speed of the bug and on the car are the same size.

1. True2. False3. Not enough info4. Not quite sure

FALSE!COMMON SENSE…DO YOU NOTICE THE CAR SLOW DOWN? DOES THE BUG NOTICE A CHANGE?

A bug and the windshield of a fast moving car collide. Tell whether the following statements are true or false, and EXPLAIN your reasoning:

d. The changes in momentum of the bug and on the car are the same size.

1. True2. False3. Not enough info4. Not quite sure

TRUE!

m Δv = m Δv’

Not to mention, Impulse = change in momentum, and we already determined they have the same impulse…

Bug Windshield Ft Ft

m Δv m Δv

•Same Impulse•Same change in momentum•Diff. masses and velocity changes!

Does a larger force always produce a larger impulse on an object than a smaller force? Explain.

1. Yes 2. No 3. Not enough info4. Not quite sure

No – not always!!

F t = F t

(1 N) (100s) = (10 N)(5s) 100 Ns = 50 Ns

YES/NO:____ EXPLANATION: A fully dressed student with a backpack is at rest in the middle of a pond on perfectly frictionless ice and must go to shore. Can this be accomplished? Use KEY TERMS to explain:

1. Yes 2. No 3. Not enough info4. Not quite sure

Yes – throw the backpack! Force = Force, Impulse = Impulse

HW – that was due last class

• #11-13, p. 100 • Texts open if needed – we are rapidly

popcorning!

• 11a) Visualize yourself on a skateboard. When you throw a ball, do you experience an impulse? Yes – push the ball, and ball

pushes you (force) for an amount of time…force x time = impulse!

HW – that was due last class

• 11b) Visualize yourself on a skateboard. When you catch a ball, do you experience an impulse?

Yes – push the ball, and ball pushes you (force) for an amount of time…force x time = impulse!

HW – that was due last class

• 11c) Visualize yourself on a skateboard. When you catch a ball, and then throw it back, do you experience an impulse?

Yes – push the ball, and ball pushes you (force) for an amount of time…force x time = impulse!

HW – that was due last class

• 11d) Visualize yourself on a skateboard. In which of the scenarios do you experience the largest impulse?

1. Catch2. Throw3. Catch an throw4. Same in all

Catch and throw – it’s like bouncing! More velocity change, so more momentum change, so more impulse!

HW – that was due last class

• 12) Why is more impulse delivered when bouncing occurs?

More velocity change, so more momentum change, so more impulse!

HW – that was due last class

• 13) Why is the Pelton wheel an improvement over a wheel with flat blades?

Worksheet you handed in for HW

• Check in w/peers or teacher to review • 3 minutes to review – remember, solutions are

online.• HOWEVER - - -IT IS YOUR responsibility to

know WHAT the solution is, and WHY it is what it is.

• Not sure? ASK FOR HELP (from a teacher or peer!)

Free Write…

• I am going to show you a series of scenarios, and tell you whether they are considered to be ‘elastic’ or ‘inelastic’ collisions

• It is your job to write/draw the scenarios you see on your T chart

• Then, comparing your columns, I want you to create a definition for “elastic collision” and “inelastic collision.”

Examples• Remember, WRITE/DRAW what you observe with enough detail to

know what’s going on later when you look at these notes!1. Newton’s Cradle – elastic

– What happens if I release…1? 2? 3? 4? 1 &1? Etc.

2. Bouncy Ball – elastic3. Glob of putty- inelastic

– Notice what happens to the side of the putty that is dropped onto the desk…

4. Cars with Velcro facing- inelastic– Notice what happens if… one is at rest, and one is moving toward the

other….or, both move toward each other…

5. Cars with magnets facing- elastic– Notice what happens if… one is at rest, and one is moving toward the

other….or, both move toward each other…

6. Billiards (pool) – elastic7. Car crash - inelastic

Create your definitions!

Volunteers to share your definitions?

Java Activity

• FOR HW - It is your job to complete #1-16; if you have time, you can try your own.

• Make sure you try this on your computer TONIGHT! That way, if you have any computer issues, you can get them taken care of TOMORROW and get this done.

• We will finish the chart and back of this packet next class… only 1-16 for HW

• Right now… we will do #1-4 together

Go to your test seats…• Normal quiz procedures apply• Open notes, not open books• No calc needed… cell phones OUT and SILENT• When done, quiz in basket upside down and

you may continue working on your HW– (make your hypotheses and try them)

• HW is #1-16 in your packet!!!• Open notes quest on Ch. 7 on Jan. 22