Momentum 3/21/16 3/21 Momentum Egg Project- Build HW: Write Report 3/22Momentum Egg Project- Drop HW: Write Report 3/23 Momentum Egg Project- Report HW: Quiz preparation 3/24 Momentum Quiz 3/25No School – Report Due 10 pm

Date: 3/21Goal: I can design and create a device that will protect an egg during a large change in momentum Bell Ringer: Web site: TB p 314

Date: 3/21Goal: I can design and create a device that will protect an egg during a large change in momentum Bell Ringer: Web site: TB p 314

Date: 3/4Goal: I can design and create a device that will protect an egg during a large change in momentum Egg Drop Project 1.Design the egg holding device - Draw a diagram of your device with notes -Think about to movie car crashes. How do they build cars to reduce the impact of the crash? 2. Create a shopping list of items to build your device

Date: 3/22Goal: I can design and create a device that will protect an egg during a large change in momentum Bell Ringer: In the picture below, a 3000kg truck moving with a velocity of 10 m/s collides with a 1000 kg car that is at rest. After the collision the vehicles are separated and the car moves away at 15m/s. What is the truck’s velocity after the collision? m 1 v 1 + m 2 v 2 = m 1 v 1 + m 2 v 2 beforeAfter

Date: 3/22Goal: I can design and create a device that will protect an egg during a large change in momentum Bell Ringer: In the picture below, a 3000kg truck moving with a velocity of 10 m/s collides with a 1000 kg car that is at rest. After the collision the vehicles are separated and the car moves away at 15m/s. What is the truck’s velocity after the collision? Before After G- m 1 =3000kg v 1 =10m/s m 1 =3000kg v 1 = ? m 2 =1000kg v 2 =0m/s m 2 =1000kg v 2 =15m/s U- v 1after E- m 1 v 1 + m 2 v 2 = m 1 v 1 + m 2 v 2 S- (3000kg(10m/s)) +(1000kg(0m/s)) = (3000kg(v)) +(1000kg(15m/s)) S kgm/s + 0= (3000kg)v kgm/s 30000kgm/s kgm/s = (3000kg)v 15000kgm/s= (3000kg)v 15000kgm/s = v 3000kg 5m/s = v

Date: 3/22Goal: I can design and create a device that will protect an egg during a large change in momentum Egg Drop Project 1.You will be called up one group at a time 2.Your design needs to be complete 2.Your shopping list must have items and total 3.Build your device- once approved

Date: 3/23Goal: I can design and create a device that will protect an egg during a large change in momentum Bell Ringer: Two cars collide in a head on collision. They lock together > < kg 1500 kg 28 m/s 20 m/s What is the speed and direction of the two cars after the collision? m 1 v 1 + m 2 v 2 = (m 1 +m 2 )v 1and2 Web site: TB p 314

Date: 3/23Goal: I can design and create a device that will protect an egg during a large change in momentum Bell Ringer: Two cars collide in a head on collision. They lock together > < kg 1500 kg 28 m/s 20 m/s What is the speed and direction of the two cars after the collision? m 1 v 1 + m 2 v 2 = (m 1 +m 2 )v 1and2 G- m 1 =1200kg v1=28m/sm2=1500kg v2=-20m/s U- v 1and 2 after E-m 1 v 1 + m 2 v 2 = (m 1 +m 2 )v 1and2 S-(1200kg(28m/s))+(1500kg(-20m/s))=(1200kg+1500kg)v 1and2 S kgm/s+ (-30000kgm/s) = 2700kg v1and2 3600kgm/s / 2700kg =v 1and2 1.3m/s= v 1and2 Web site: TB p 314

Date: 3/24 Goal: I can design and create a device that will protect an egg during a large change in momentum Bell Ringer: Two cars collide in a head on collision and stick together > < kg 1000 kg 23 m/s 29 m/s What is the speed and direction of the two cars after the collision? m 1 v 1 + m 2 v 2 = (m 1 +m 2 )v 1and2 Web site: TB p 314

Date: 3/24 Goal: I can demonstrate my understanding of momentum Two eggs of the same mass are thrown and go through the same change in momentum. One hits a wall and cracks and the other hits a cushion and does not crack. Why did one egg crack and the other did not?

Date: 3/24 Goal: I can demonstrate my understanding of momentum Two eggs of the same mass are thrown and go through the same change in momentum. One hits a wall and cracks and the other hits a cushion and does not crack. Why did one egg crack and the other did not?

Why does an egg break or not break? An egg dropped on a tile floor breaks, but an egg dropped on a pillow does not. Why? FΔt= mΔv In both cases, m and Δv are the same. If Δt goes up, what happens to F, the force? Right! Force goes down. When dropped on a pillow, the egg starts to slow down as soon as it touches it. A pillow increases the time the egg takes to stops.

Practice Problem A 57 gram tennis ball falls on a tile floor. The ball changes velocity from -1.2 m/s to +1.2 m/s in 0.02 s. What is the average force on the ball? Identify the variables: Mass = 57 g = kg Δvelocity = +1.2 – (-1.2) = 2.4 m/s Time = 0.02 s using FΔt= mΔv F x (0.02 s) = (0.057 kg)(2.4 m/s) F= 6.8 N

Car Crash Would you rather be in a head on collision with an identical car, traveling at the same speed as you, or a brick wall? Assume in both situations you come to a complete stop. Take a guess

Car Crash (cont.) Everyone should vote now Raise one finger if you think it is better to hit another car, two if it’s better to hit a wall and three if it doesn’t matter. And the answer is…..

Car Crash (cont.) The answer is… It Does Not Matter! Look at FΔt= mΔv In both situations, Δt, m, and Δv are the same! The time it takes you to stop depends on your car, m is the mass of your car, and Δv depends on how fast you were initially traveling.

Egg Drop connection How are you going to use this in your egg drop? Which of these variables can you control? FΔt= mΔv Which of them do you want to maximize, which do you want to minimize (note: we are looking at the force on the egg. Therefore, m represents the egg mass, not the entire mass of the project)

From the California Standards Test Copyright © 2004 California Department of Education.

From the California Standards Test Copyright © 2004 California Department of Education.

From the California Standards Test Copyright © 2004 California Department of Education.

Date: 3/24Goal: I can design and create a device that will protect an egg during a large change in momentum Bell Ringer: Two cars collide in a head on collision. They lock together > < kg 1000 kg 23 m/s 29 m/s What is the speed and direction of the two cars after the collision? m 1 v 1 + m 2 v 2 = (m 1 +m 2 )v 1and2 G- m 1 =1100kg v1=23m/sm2=1000kg v2=-29m/s U- v 1and 2 after E-m 1 v 1 + m 2 v 2 = (m 1 +m 2 )v 1and2 S-(1100kg(23m/s))+(1000kg(-29m/s))=(1100kg+1000kg)v 1and2 S (-29000) = 2100 v1and /2100=v 1and m/s= v 1and2

Date: 3/24Goal: I can design and create a device that will protect an egg during a large change in momentum Analysis Questions: Calculate the potential energy of the egg before it is dropped. GPE=? Calculate the kinetic energy of the egg when it reaches the floor (just before impact). KE bottom = ? Calculate the velocity of the egg when it reaches the floor (just before impact). V 2 =2gh (before) Calculate the velocity of the egg after it collides with the floor (after impact). -Need to measure the height of the bounce after it hits the floor and use V 2 =2gh (After) What was the change in momentum of the egg during the collision with the floor.  P=m(v before -v after ) Calculate the impulse (change in Momentum = m  v) of the egg during its impact.

Date: 3/23Goal: I can design and create a device that will protect an egg during a large change in momentum Independently Read TB p min

Date: 3/6Goal: I can design and create a device that will protect an egg during a large change in momentum Momentum-Collision activity- How does mass and velocity affect collision, Momentum video “Understanding Car Crashes”, TB p TB p ,6 and p ,2,6,7, TB p 315 sample problems, Egg Drop Lab Activity

Date: 2/26Goal: I can explain how the change in momentum can affect an object Due today Notebook – TB p. 306 and take CN – TB p. 308 Essential Questions – HW: TB p. 307 # 1-3 – HW: TB: p. 315 #1-3 WB p Momentum video and Worksheet WB p

Date: 2/26Goal: I can explain how the change in momentum can affect an object Quiz practice questions p ,6 p ,2,6,7

M As I'm sure you suspect, momentum in physics is different from "momentum" in sports on tv, as in "Yes, Chris, the Bengals really have momentum on this drive!". However, physics momentum is related to football momentum in that both concepts refer to how difficult it will be to stop something.What makes an object difficult to stop? Its mass, for one thing. After all, mass measures the inertia of an object - how much the object resists accelerating. Certainly, more mass means more momentum - the momentum of an object is directly proportional to its mass. Twice the mass means twice the momentum. Momentum is not the same as mass, though. For one thing, an object that is not moving has no momentum, no matter how much mass it has.Fast objects are also difficult to stop. Bullets have a very small mass, but you wouldn't want to try and stop one! More speed means more momentum - momentum is directly proportional to velocity. Twice the speed means twice the momentum.Since the momentum of an object is directly proportional to both its mass and its velocity,Momentum = (mass)(velocity) = mvMomentum is a vector quantity. Its direction is the same as the direction of the object's velocity.

Momentum 3/21/16 Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories. Students design a device that minimizes the force on a macroscopic object during a collision. In the design, students: i.Incorporate the concept that for a given change in momentum, force in the direction of the change in momentum is decreased by increasing the time interval of the collision (FΔt = mΔv); and ii. Explicitly make use of the principle above so that the device has the desired effect of reducing the net force applied to the object by extending the time the force is applied to the object during the collision. b In the design plan, students describe the scientific rationale for their choice of materials and for the structure of the device. 2Describing criteria and constraints, including quantification when appropriate

Momentum 3/21/16 Students describe and quantify (when appropriate) the criteria and constraints, along with the tradeoffs implicit in these design solutions. Examples of constraints to be considered are cost, mass, the maximum force applied to the object, and requirements set by society for widely used collision-mitigation devices (e.g., seatbelts, football helmets). 3 Evaluating potential solutions a Students systematically evaluate the proposed device design or design solution, including describing the rationales for the design and comparing the design to the list of criteria and constraints. b Students test and evaluate the device based on its ability to minimize the force on the test object during a collision. Students identify any unanticipated effects or design performance issues that the device exhibits. 4 Refining and/or optimizing the design solution a Students use the test results to improve the device performance by extending the impact time, reducing the device mass, and/or considering cost-benefit analysis.