DAY 54

NGSS Standard (this is what we're learning with this unit)

Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration. [Clarification Statement: Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object sliding down a ramp, or a moving object being pulled by a constant force.] [Assessment Boundary: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.]

#Goals: SWBAT...

1. Recall Newton's Three Laws from memory

2. Maintain professional (quiet, thoughtful, respectful, focused on physics) behavior throughout the class period.

3. Help group-mates find answers by asking them guiding questions

4. Match activities with one of Newton's Three Laws

Warm-Up (6min) 

Copy and fill in (or choose) the correct answers for the following:

CLASSWORK

1. #054A: Sir Isaac Newton Olympics

    - This is your chance to put all the learning you've done into motion. Before, during, and after, be thinking and talking about which law fits with each activity. 

    - On your handout, fix Station #3, question 3. It should read "pulls" not "pushes"

    A. Mr. A models steps (LINK) for each station

    B. Complete each activity and questions within the allotted time

    C. Staple your group-mates completed worksheets together, and turn them in for credit

    - handout LINK (start on page 3)

At Home Learning (HW) 

1. Begin reviewing by answering questions in the link below:

NGSS Standard (this is what we're learning with this unit)

Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration. [Clarification Statement: Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object sliding down a ramp, or a moving object being pulled by a constant force.] [Assessment Boundary: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.]

#Goals: SWBAT...

1. Draw correct FBD's, with appropriate vector magnitude and direction.

2. Use FBD's to find Net Force

3. Describe the relationship between mass, net force, and acceleration

WARM-UP

Construct a free-body diagram for the following object; label the forces according to type. Use the approximation that g = 9.8 m/s2 to determine the magnitude of all forces and the net force and acceleration of the object.

- A 2-kg box is falling from a tree. Ignore air resistance.

CLASSWORK

1. #053A continued: Quiz Practice & Wrapping Up Newton's 2nd Law

Learning at Home (HW)

- Complete the Apprentice and Master and Wizard sections of 053A (if you didn't finish in class). 

Goals: SWBAT...

1. Answer the following question: Momentum - how can you prove it is conserved?

Warm-Up (5min): 

1. When considering an isolated system, both before and after a collision, how could you tell if momentum is conserved?

2. Is momentum conserved or not conserved in each of the following scenarios? Support your answer with math

CLASSWORK

1. #054A: Solving Explosion Momentum Problems

2. #054B: Practice Problems:

1. Two soda cans are at rest on a stand. A firecracker is placed between the cans and lit. The firecracker explodes and exerts equal and opposite forces on the two cans. Assuming the system of two cans to be isolated, the post-explosion momentum of the system ____.

a. is dependent upon the mass and velocities of the two cans

b. is dependent upon the velocities of the two cans (but not their mass)

c. is typically a very large value

d. can be a positive, negative or zero value

e. is definitely zero

 

2. Students of varying mass are placed on large carts and deliver impulses to each other's carts, thus changing their momenta. In some cases, the carts are loaded with equal mass; in other cases they are unequal. In some cases, the students push off each other; in other cases, only one team does the pushing. For each situation, list the letter of the team that ends up with the greatest momentum. If they have the same momentum, then do not list a letter for that situation. Enter the four letters (or three or two or ...) in alphabetical order.

 

3. Two ice dancers are at rest on the ice, facing each other with their hands together. They push off on each other in order to set each other in motion. The subsequent momentum change (magnitude only) of the two skaters will be ____.

a. greatest for the skater who is pushed upon with the greatest force

b. greatest for the skater who pushes with the greatest force

c. the same for each skater

d. greatest for the skater with the most mass

e. greatest for the skater with the least mass

4. A 62.1-kg male ice skater is facing a 42.8-kg female ice skater. They are at rest on the ice. They push off each other and move in opposite directions. The female skater moves backwards with a speed of 6.22 m/s. Determine the post-impulse speed of the male skater.

 

5. A 1.5-kg cannon is mounted on top of a 2.0-kg cart and loaded with a 105.4-gram ball. The cannon, cart, and ball are moving forward with a speed of 1.27 m/s. The cannon is ignited and launches the ball forward with a speed of 75 m/s. Determine the post-explosion velocity of the cart.

3. #053: Extra Credit Presentations

At Home Learning (HW) 

1. Complete the classwork from #054B