Ch3+Safety+LP

=Chapter 3=

Section 1
What do you see? - There is a car crash. The car is smashing into the wall. The teddy bear was in the back seat and it is being launched forward. The driver is moving forward into the steering wheel.

What do you think? - You should always wear a seat belt, and make sure you are sitting forward. If you do not wear a seat belt you will go through the front of the car.

Investigation Section 1
St ep 2: a) Novice Analyst

Step 3: Copy this table onto your wiki and then complete it. The explanation is on p.262 of the textbook. (yes/no) || New Cars (1,2,3) ||
 * Safety features || Means of protection || Pre-1960 cars
 * seat belts || It holds you back and stops you from moving after stop || no || 1 ||
 * head restraints || Keeps neck from breaking || no || 1 ||
 * front airbags || Provides cushioning in the collision || no || 1 ||
 * back up sensing system || It helps you tell what behind you while driving || no || 3 ||
 * front crumple zones || Provides room for your car to crash without hurting you || no || 1,2 ||
 * rear crumple zones || Provides room for crumple in the back of your carwe took a piece of tape and folded it over so there was no sticky part. We then twirled the end to make tying it easier. We put the tape belt around "her" waist and tied it around the bottom of the cart. Despite my face in the after picture, the tape actually worked well because our figure was unharmed and barely moved. || no || 2 ||
 * side-impact beams in doors || Protects the door because there made of aluminum || no || 2 ||
 * shoulder belts for all seats || Provides protection for the upper body || no || 1 ||
 * anti-lock braking systems (ABS) || Creates friction to stop in bad weather || no || 2 ||
 * tempered shatterproof glass || Stops glass from shattering in a collision || yes || 1 ||
 * side airbags || Protects from side collision || no || 2 ||
 * turn signals || Advises the person in front of you that you are turning || yes || 1 ||
 * electronic stability control || helps resist rollovers || no || 2,3 ||
 * energy-absorbing collapsible steering column || prevents chest trauma || no || 1 ||

Physics talk Ralph Nader wrote a book called "Unsafe at Any Speed" showing that cars were not safe and they needed to be fixed to help save lives. It talked about having a seatbelt in vehicles, hard chrome dashboards, and solid steering columns. Since then manufacturers have made there cars much safer.

Checking Up 1. They improved there cars by putting seatbelts in cars, hard chrome dashboards, and solid steering. 2. Not having head restraints and seatbelts can cause major injuries to the drivers and passengers.

Physics to Go 1. seat belts, head rests, front airbags, back up sensing system, front crumple, and turn signals. 2. helmet, pads for elbows, knees, and wrists 3. Helmet, pads for elbows, knees, and wrists 4. Helmet, pads for elbows, knees, and wrists 5. pads, turn signals, head restraints ect.

What do you think Now? - Be relaxed and wear a seatbelt. Make sure your car is up to date when you are driving your car.

Inquiring Further 1,2 (Extra Credit due Monday) 1. I interviewed my Dad who owns and works on his own cars. I asked him a couple questions about changes in cars throughout the years of his life. He said that the car has changed drastically since the first time he drove a car. His first car was a corvette. It did not have power steering. No almost every single car has to have power steering. Another adjustment is the seatbelt's in the car. He said that in his car they were the same as now, but in others they were different. They did not go across the shoulders. Only went across the waist. He said that now a days everybody is worried about the safety so all of the advertisements show safety more than anything else.

2. Sports cars are made to go fast but lately they have been made to have extra safety features. In trucks they have put in more safety features because they are so big. They are very dangerous because of the brake systems., but one major change is through four wheel drive. They have put more four wheel drive in cars than they had back then. They have been trying to get more traction between the car tires and the roads. The four wheel drive allows there to be more traction.

Investigate X2: Newton's FIrst Law and Seatbelts
Objectives:
 * What happens to a passenger involved in a car accident without and with a seatbelt?
 * What factors affect the passenger’s safety after a collision?
 * How would a seat belt for a race car be different from one available on a regular car?

Hypothesis: Respond to each of the above objectives fully. - That passenger will be thrown forward into and through the windshield. - The seat belts, headrest, air bag. - The seat belt has to be stronger than a regular car because it is going much faster than a normal car and when it crashes it needs to withstand the impact of the wall or car. Materials: List any materials used and draw a labeled diagram of your set-up (alternatively, include a snapshot or video).

Procedure:
 * 1) Make a clay figure and then place the figure in the cart.
 * 2) Arrange a ramp so that the endstop is at the bottom of the ramp.
 * 3) Adjust the height of the ramp to make a very shallow incline.
 * 4) Send the cart down the ramp.
 * 5) Very gradually increase the height of the ramp until significant “injury” happens to your figure. Make a note of this height.
 * 6) Fix your clay figure. Create a seatbelt for the figure and take a "Before" picture and post in your data table.
 * 7) Send your cart and passenger down the ramp at the same height as in Step 5. Be sure to record your observations specifically and carefully. Take an "After" picture and post in your data table to supplement your written observations.
 * 8) Repeat Steps 6 and 7, using different types of material for the seatbelt.

Data and observations: Injury Height with no seatbelt: 3 textbooks

through his body and sliced his neck. || 6 ||
 * Type of Seatbelt || Before Picture || After Picture || Description and Observations || Group ||
 * Thread || [[image:111Photo_45.jpg]] || [[image:111Photo_46.jpg]] || Arm chopped off. The seat belt cut
 * Wire || [[image:hershey_kissboybefore.jpg]] || [[image:hersheykissafter.jpg]] || The wire was put around the passenger pretty tightly in order for him to stay on the cart after the collision. The wire was so tight that it sliced his arms and chest. The wire material is not a good idea because it can harm the person even if the collision wasnt that bad. || 1 ||
 * String || [[image:stringgPhoto_86.jpg]] || [[image:strringgPhoto_87.jpg]] || Our seatbelt made of string went around the chest. After going down the ramp, our passenger was still in the cart without any injuries. || 2 ||
 * Yarn || [[image:sgrant11.jpg]] || [[image:sgrant22221.jpg]] || Our observation of the yarn seat belt is that when the accident occurred, the figure slammed forward. This shows that the yarn is not sturdy enough to prevent an injury in an accident. ||  ||
 * Ribbon || [[image:Photo_38lp.jpg]] || [[image:Photo_41lp.jpg]] || We made a seatbelt out of ribbon that went around his waist shoulders and chest. When the cart went down the ramp, the seatbelt held him in place and the clay person didn't leave the cart. || 3 ||
 * 1- in masking || [[image:Photo_7758.jpg]] || [[image:Photo_7662.jpg]] || we took a piece of tape and folded it over so there was no sticky part. We then twirled the end to make tying it easier. We put the tape belt around "her" waist and tied it around the bottom of the cart. Despite my face in the after picture, the tape actually worked well because our figure was unharmed and barely moved. || 4 ||


 * Read the Physics Talk p268 - 271 before answering the following questions. *

Questions:
 * 1) Define the terms: inertia, force and pressure.
 * 2) inertia - a tendency to do nothing or to remain unchanged
 * 3) force - strength or energy s an attribute of physical action or movement
 * 4) pressure - the continuous physical force exerted on or against an object by something in contact with it
 * 5) In the collision, the car stops abruptly. What happens to the “passenger”?
 * 6) The passengers body goes forward off the car.
 * 7) What parts of your passenger were in greatest danger (most damaged)?
 * 8) The head, arms, and legs
 * 9) What does Newton’s first law have to do with this?
 * 10) Any object in motion stay in motion until a force acts upon them. the force (human) gets speed until it hits something and then flies off the cart.
 * 11) What materials were most effective as seatbelts? Why?
 * 12) The softest, but strongest material was the best. Like ribbon, string, and yarn
 * 13) Use Newton's first law of motion to describe the three collisions.
 * 14) The car colliding with whatever it is crashing into. Then your body crashes into something. Then your organs crash inside of you. You can get a concussion.
 * 15) Why does a broad band of material work better as a seatbelt than a narrow wire?
 * 16) The wire is very thin and can cut the person if the car is going fast enough

Conclusion: · Using Newton's First law of Motion, explain why a seat belt is an important safety feature in a vehicle. What factors affect the effectiveness of a seatbelt? What would you need to consider when designing a seatbelt for a race car? Use specific observations from this investigation to support your answers to these questions. · Explain at least 1 cause of experimental error. Be sure you describe a specific reason. · How would you improve the results of this lab? (In other words, what would you change about the materials or procedure to eliminate or reduce the experimental error you describe above?)

USE THE RUBRIC TO MAKE SURE YOU HAVE INCLUDED ALL REQUIREMENTS!

Investigate X3: Energy and Air Bags
Objective:
 * How does an air bag protect you during an accident?

Hypothesis: Respond to the objective fully. - The airbag stops the person from moving forward and provides a cushion to hit into instead of hitting the metal in your car. Materials: List any materials used and draw a labeled diagram of your set-up (alternatively, include a snapshot or video).

Procedure:

Note: You may want to use the available technology to take "Before" and "After" pics to post in your data table to assist and elaborate on your written descriptions.

1. Measure the height of your egg #1. 2. Place an egg in a ziplock bag, squeezing out all of the air in the bag before sealing. 3. Hold a ruler up on the table vertically. Hold the egg vertically at the 2 cm mark. (Keep the excess bag on top.) Drop it. Record your observations. 4. Hold the egg the same exact way at the 4-cm mark and repeat. Continue this process until the egg shell is slightly cracked. 5. Continue until the egg is smashed and the yolk leaks out. Measure the amount of egg still undamaged. How much of the egg is smashed? Be sure to record detailed observations. 6. Fill a bowl with rice and place the bowl inside of the box lid. 7. Measure the height of your egg #2. 8. Drop the egg from the smash height (Step 3). Measure the amount of egg sticking up out of the rice bed. How much of the egg is buried in the rice? Also, record your observations. 9. Repeat this, increasing the height in 2-cm increments until the egg is cracked, and then smashed.

//**Data and observations:** Add more columns/row as needed.//
 * **Egg #** || **Drop Height** || **Cracked or Smashed?** || **Description and Observations** || **Dented flour** ||
 * 1 m: .5638 kg h: .055 m || 2 cm || cracked || a small crack ||  ||
 * 1 || 4 cm || cracked || slightly more cracked ||  ||
 * 1 || 6 cm || cracked || dented but no yolk ||  ||
 * 1 || 8 cm || cracked || bigger crack ||  ||
 * 1 || 10 cm || cracked || continues to crack a little bit ||  ||
 * 1 || 12 cm || cracked || a piece of the shell cracked off ||  ||
 * 1 || 14 cm || cracked || more cracked, still no yolk ||  ||
 * 1 || 16 cm || cracked || more shell broke off ||  ||
 * 1 || 18 cm || cracked || more cracks and more shell ||  ||
 * 1 || 20 cm || cracked || cracked further ||  ||
 * 1 || 22 cm || cracked || shell broke off ||  ||
 * 1 || 24 cm || cracked || whites of the egg came out! ||  ||
 * 1 || 26 cm || cracked || more whites are oozing ||  ||
 * 1 || 28 cm || smashed || YOLK IS OUT! ||  ||
 * 2 m: .5757 kg h: .056 m || 28 cm || nothing happened to the egg ||  || .027 m ||
 * 2 || 28 || nothing happened ||  ||   ||
 * 2 || 30 || nothing happened ||  ||   ||
 * 2 || 32 || nothing happened ||  ||   ||
 * 2 || 34 || nothing happened ||  ||   ||
 * 2 || 36 || nothing happened || no damage || .026 ||
 * 2 || 40 || nothing happened || no damage || .028 ||
 * 2 || 44 || nothing happened || no damage || .035 ||
 * 2 || 48 || nothing happened || no damage || .038 ||
 * 2 || 52 || nothing happened || no damage || .039 ||
 * 2 || 56 || nothing happened || no damage || .04 ||
 * 2 || 60 || nothing happened || no damage || .04 ||
 * 2 || 72 || nothing happened || no damage || .041 ||
 * 2 || 1 meter || nothing happened || no damage || .045 ||
 * 2 || ceiling || missed || broke ||  ||



Calculations: Show equation(s), numbers plugged in, and answer with correct units. Add columns in your data table to include these results.
 * What is the gravitational potential energy in each trial?
 * How much work is done in each trial?
 * How much force was used to stop the egg in each case of steps 5, 8 and 9.


 * Read the Physics Talk p279 - 287 before answering the following questions. *

Questions:
 * 1) This investigate is an analogy for a person in an automobile collision. What does the egg represent? What does the table represent? What does the rice represent?
 * 2) The egg represents the human. The table is the other car or wall. The rice is the air bag.
 * 3) Define the terms: Kinetic Energy and Work.
 * 4) Kinetic Energy is 1/2mv^2 (1/2 * mass * velocity^2)
 * 5) Work is fd (force * displacement)
 * 6) What factors determine an object's kinetic energy?
 * 7) The mass and the velocity of the object
 * 8) When work is done on an object, what is the effect on the object's kinetic energy?
 * 9) The displacement of the object
 * 10) How does the force needed to stop a moving object depend on the distance the force acts?
 * 11) If the speed is to fast and the object comes to a rapid stop then it will exert more force.
 * 12) What difference does a soft landing area make on a passenger during a collision?
 * 13) It creates a cushion and the passenger does not get as injured as they would if there was no cushion
 * 14) How does a cushion reduce the force needed to stop a passenger?
 * 15) It provides a softer landing spot so it doesn't hit the hard surface and cause damage.
 * 16) What does the law of conservation of energy have to do with this?
 * 17) The law states that an object will continue in motion until another object acts upon it.

Conclusion: · Using the law of conservation of energy, explain how an air bag can protect you during an accident. Use specific observations from this investigation to support your answers to these questions. · Explain at least 1 cause of experimental error. Be sure you describe a specific reason. · How would you improve the results of this lab? (In other words, what would you change about the materials or procedure to eliminate or reduce the experimental error you describe above?)

USE THE RUBRIC TO MAKE SURE YOU HAVE INCLUDED ALL REQUIREMENTS!

Momentum: quantity of motion described by the product of mass and velocity p = (m)(v) large mass that has a small velocity small mass that has a large velocity large mass that has a large velocity

Physics to Go 1. If they have the same mass then the first car stops and the momentum gets transfered to the car that it hits. The second car will continue at the same speed as the other car. 4. They have more momentum so it will be harder to knock them down 5. It is whatever car has the smallest momentum 6. 1/10 velocity

Investigate X6: Momentum and Inelastic Collisions
Objective: What physics principles do the traffic-accident investigators use to "reconstruct" the accident?

Materials: List any materials used and draw a labeled diagram of your set-up (alternatively, include a snapshot or video).

Procedure:
 * 1) Place a motion detector at the right end of a track. Open up data studio. Dump "Velocity" into "Graph" display, and enlarge this.
 * 2) Place a cart on the middle of the track with the velcro to the right. Call this the "target cart." Place a second identical cart on the right end of the track. Call this the "Bullet cart".
 * 3) Click "Start" on Data Studio, and then push the bullet cart very gently towards the target cart so that they collide and stick together. You may need to practice this a few times. Be sure to get your body out of the way of the motion detector!
 * 4) Examine the graph produced by the motion detector. Using the Smart Tool, find the velocity right before and right after the collision. Record this in your data table.
 * 5) Vary the masses of the carts and repeat the process 5 times.

Data and observations: Add more columns/row as needed.
 * Mass of Bullet Cart (kg) || Mass of Target Cart (kg) || Speed of Bullet Cart(m/s) || Speed of Target cart (m/s) || Combined masses (kg) || Final Velocity of both carts (m/s) ||
 * .501 || .499 || .85 || 0 || 1.009 || .42 ||
 * .726 || .499 || .84 || 0 || 1.225 || .49 ||
 * 1 || .499 || .65 || 0 || 1.499 || .50 ||
 * 1.25 || .499 || .79 || 0 || 1.749 || .61 ||
 * 1.5 || 1 || .75 || 0 || 2.5 || .45 ||
 * 1 || 2 || .76 || 0 || 3 || .30 ||

Calculations: Show equation(s), numbers plugged in, and answer with correct units. Add columns in your data table to include these results.
 * 1) Find the initial momentum of the bullet cart for each trial.
 * 2) Find the initial momentum of the target cart for each trial.
 * 3) Find the sum of the initial momenta of the two carts for each trial.
 * 4) Find the final momentum of the combined carts for each trial.


 * Read the Physics Talk p312 - 315 before answering the following questions. *

Questions:
 * 1) Compare the initial momenta (calc 3) to the final momentum (calc 4). (Allow for minor variations due to uncertainties of measurement.)
 * 2) There is a little difference but they are the same
 * 3) List the 6 types of collisions (top of page 312) and a brief description.
 * 4) One moving object hits a stationary object and both stick together and move off at the same speed
 * 5) Two stationary objects explode by the release of a spring between them and move off at the same speed
 * 6) One moving object hits a stationary object. The first object stops, and the second objects moves off
 * 7) One moving object hits a stationary object, and both move off at different speeds
 * 8) Two moving objects collide, and both objects move at different speeds after the collision
 * 9) Two moving objects collide, and both objects stick together and move off at the same speed
 * 10) Which types of collisions are definitely inelastic? How do you know?
 * 11) Collision 2,3,5
 * 12) Which types of collisions are definitely elastic? How do you know?
 * 1,4,6
 * 1) Define the law of conservation of momentum.
 * 2) In a system consisting of bodies on which no outside forces are acting; the total momentum of the system remains the same.
 * 3) Use the law of conservation of momentum to describe what happens when a cue ball hits the 15 balls in the middle of the pool table.
 * 4) The pool ball transfers all of its momentum into the balls and causes them to travel with less momentum than the white ball but still move.

Conclusion: · Based on the law of conservation of momentum, how can the traffic-accident investigators use to "reconstruct" the accident? What does it mean to "conserve" momentum? · Explain at least 1 cause of experimental error. Be sure you describe a specific reason. · How would you improve the results of this lab? (In other words, what would you change about the materials or procedure to eliminate or reduce the experimental error you describe above?)

USE THE RUBRIC TO MAKE SURE YOU HAVE INCLUDED ALL REQUIREMENTS!

Physics to Go

2. person --> <-- person <--person,person-->

2a. p=mv Cart A: =(1)(2)  = 2 kg (m/s)  Cart B = (1)(-2) = -2 kg (m/s)

2b. momentum before mvi + m2vi2 = P before (1kg)(2m/s) + (1kg)(-2m/s) 0 = Pbefore

2c. momentum after mvi + m2vi2 = mvf + m2vf2 (1kg)(2m/s) + (1kg)(-2m/s) = (1kg)(vf) + (1kg)(Vf2) 0 = 2kg(vf) 0 = Vf..... finally velocity of both carts is zero momentum after the collision = 0.

3. mvi + m2vi2 = mvf + m2vf2 mVi + 0 = m(4) + m(4) mVi = 8m vi= 8 m/s momentum, is transferred to B.

5. After the two carts collide vehicle B gains momentum that the first vehicle A lost. (4000 kg m/s) The momentum of the systmen is zero because the momentum is transfered to cart B.

6. mvi + m2vi2 = mvf + m2vf (2000kg)(3m/s) + (2000kg)(2m/s)= 2000Vf + 2000Vf 10000 = 4000 Vf 2.5 m/s = Vf

7. mvi + m2vi2 = mvf + m2vf2 80kg(10m/s) + (100kg)(8m/s) = 80kg(Vf) + (100kg)(9.78m/s) 622 = 80Vf 7.8 m/s = Vf

8. mvi + m2vi2 = mvf + m2vf2 (3)(2) + (1)(-2) = (3)(0) + (1)(Vf) 4 m/s = Vf2

9.-12 m/s 10. m1= .35 kg m2= .06 kg vi= 20 m/s v2= -30 m/s v1f =10 m/s v2f= ? m1v1 + m2v2 = m1v1f + v1f + v2f (.35)(20) + (.06) = (.35)(10) + .06v2f vf = 28.3 m/s

11. 12. 13. 14.

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