jrosenberg3

Jordan Rosenberg's Wikilog toc Period 6 CP Physics - Mrs. Burns - 2011

Chapter 3 - Section 1
Two crash dummies in a car crash test, the airbag is smashed into the adults face, the cars front caved in. The teddy bear was in the back seat, it went flying. The driver is going forward into the airbag.
 * __What Do You See?__**

If you wear a seat belt and you have an installment of airbags you should be much safer.
 * __What Do You Think?__**

Four close friends are together in a car crash and killed saturday morning at Crest Hill. The reason the crash was caused was told by the police that they all were speeding. They all grew up together and sadly all died Crest Hill Police Chief Dwayne Wilkerson said speed may have been a factor in the crash, which is under investigation. According to their family and friends, the four friends who grew up in Romeoville were typically cheery and always having a good time. They are still in the works for typical equipment that wasn't working or investigating if they were not wearing seatbelts but we will find the true answer soon.
 * __Article__**


 * __Investigate__**

2.) 12/15, I am an assistant analyst, some of the information surprised me. 3.) (yes/no) || New Cars (1,2,3) ||
 * ** Safety features ** || Means of protection || Pre-1960 cars
 * seat belts || keeps driver and passengers inside the car || no || 1, all ||
 * head restraints || prevents whiplash || no || 1, all ||
 * front airbags || cushions during a collision || no || a, all (driver's side) ||
 * back up sensing system || allows you to see in blind spots while backing up || no || 3, few ||
 * front crumple zones || increase collision distance reducing impact || no || 1, 2, all, some ||
 * rear crumple zones || increase collision distance reducing impact || no || 2, some ||
 * side-impact beams in doors || resists side penetration || no || 2, some ||
 * shoulder belts for all seats || keeps passenger in seats during collision || no || 1, all ||
 * anti-lock braking systems (ABS) || helps maintain control/ prevents skids || no || 2, some ||
 * tempered shatterproof glass || helps prevent cuts || yes || 1, all ||
 * side airbags || protects head/torso in side collisions || no || 2, some ||
 * turn signals || warns other drivers of actions || yes || 1, all ||
 * electronic stability control || helps resist rollovers || no || 2, 3, some, few ||
 * energy-absorbing collapsible steering column || prevents chest trauma || no || 1, all ||

__**Physics Talk**__ Vehicle Safety people in vehicles are not the only ones in danger- pedestrians are too manufacturers have to be aware of vehicle safety not safe: no seat belts, chrome dashboards, solid steering columns four wheel drive - more accidents maybe due to tendency of drivers to increase speed under the impression that the safety features will protect them

1.) They have added seat belts, they no longer have hard chrome dashboards, and they don't have solid steering columns 2.) This could be due to the growing number of kilometers traveled by cars with 4WD, it could also be due to the tendency of some drivers to increase speed under the impression that the safety features will protect them.
 * __Checking Up__**

1.) 10 safety features: turn signals (F,R,S), side airbags (S, T), tempered shatterproof glass (F,R,S,T), shoulder belts (F,R,S,T), side-impact beams in doors (S), rear crumple zones (R), front crumple zones (F), seat belts (F,R,S,T), head restraints (F,R), front airbags (F, R, T) 2.) Bike safety features: helmet, wrist guards, knee pads, reflector 3.) In-line skating safety features: helmet, knee pads, wrist guards, shin guards, thick wheels 4.) Skate boards safety features: helmet, knee pads, wrist guards, a touch surface
 * __Physics To Go__**

You should be much safer with seat belts/ shoulder belts, airbags, padded dash, and crumple zones. If you don't wear your seat belt you are much less safe.
 * __What Do You Think Now?__**

Chapter 3 - Section 2
__**Investigate**__
 * 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?

A passenger without a seat belt will likely go through the windshield. With a seatbelt will at least get whiplash. Seatbelt, speed of collision, and impact position. Seat belts in race cars are much more secure. They hold you back.
 * Hypothesis:**


 * 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.

through his body and sliced his neck. || 6 ||
 * **//Type of Seatbelt//** || //**Before Picture**// || //**After Picture**// || //**Description and Observations**// || //**Group**// ||
 * Thread || [[image:woods-wiki:111Photo_45.jpg width="147" height="109" caption="111Photo_45.jpg"]] || [[image:woods-wiki:111Photo_46.jpg width="127" height="95" caption="111Photo_46.jpg"]] || Arm chopped off. The seat belt cut
 * Wire || [[image:proringer:hershey_kissboybefore.jpg width="151" height="111" caption="hershey_kissboybefore.jpg"]] || [[image:proringer:hersheykissafter.jpg width="148" height="109" caption="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:activephysics-pvrhsd:stringgPhoto_86.jpg width="242" height="180" caption="stringgPhoto_86.jpg"]] || [[image:activephysics-pvrhsd:strringgPhoto_87.jpg width="242" height="180" caption="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:activephysics-pvrhsd:sgrant22221.jpg width="190" height="140" caption="sgrant22221.jpg"]] || [[image:activephysics-pvrhsd:sgrant11.jpg width="190" height="140" caption="sgrant11.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. || 5 ||
 * Ribbon || [[image:activephysics-pvrhsd:Photo_38lp.jpg width="160" height="120" caption="Photo_38lp.jpg"]] || [[image:activephysics-pvrhsd:Photo_41lp.jpg width="190" height="140" caption="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:activephysics-pvrhsd:Photo_7758.jpg width="242" height="180" caption="Photo_7758.jpg"]] || [[image:activephysics-pvrhsd:Photo_7662.jpg width="242" height="180" caption="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 ||

Questions:
 * 1) Define the terms: inertia, force and pressure.
 * 2) Inertia - to remain unchanged until a force acts upon you
 * 3) Force- strength or energy as attribute to a 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) He remains in inertia and keeps traveling until something stops him
 * 7) What parts of your passenger were in greatest danger (most damaged)?
 * 8) His head
 * 9) What does Newton’s first law have to do with this?
 * 10) An object in motion stays in motion unless a force is acted upon it, and the person kept traveling until something stopped him
 * 11) What materials were most effective as seatbelts? Why?
 * 12) Use Newton's first law of motion to describe the three collisions.
 * 13) Why does a broad band of material work better as a seatbelt than a narrow wire?
 * 14) It has more surface on the body and thus applies less force on any specific area because it is distributed uniformly throughout the belt.

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?)
 * A seat belt is a very important safety feature because it stops your inertia after a car crash.
 * If the seat belt wasn't securely or correctly made
 * I would create a head rest on the cart to be able to make a better seat belt and make a more realistic scenario

__**Investigate**__
 * Objective:**
 * How does an air bag protect you during an accident?

The airbag basically cushions the impact from a crash, when it deploys you hit that instead of a solid steering wheel.
 * Hypothesis:**

Egg, bag, meter stick, flour, bowl
 * Materials:**


 * Procedure:**

// 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.// 0.041m not cracked 0.012 cracked GPE = mgh GPE = W
 * **Egg #** || **Drop Height (m)** || **Cracked or Smashed?** || **Description and Observations** || **Weight** (kg) || **Egg height** (m) || **depth into flour** (m) ||
 * 1 || 0.02 || very small crack || no visible crack, but audible one || 0.057 || 0.053 ||  ||
 * 1 || 0.04 || small crack || crack was visible and audible || 0.057 || 0.053 ||  ||
 * 1 || 0.06 || crack || crack was visible and audible, slight liquid seepage || 0.057 || 0.053 ||  ||
 * 1 || 0.08 || crack || hole in egg but membrane intact || 0.057 || 0.053 ||  ||
 * 1 || 0.1 || bad crack || top flattened || 0.057 || 0.053 ||  ||
 * 1 || 0.12 || bad crack || cracks are getting worse || 0.057 || 0.053 ||  ||
 * 1 || 0.14 || bad crack || cracks are really bad || 0.057 || 0.053 ||  ||
 * 1 || 0.16 || bad crack || cracks are really bad || 0.057 || 0.053 ||  ||
 * 1 || 0.18 || smashed || total annihilation || 0.057 || 0.053 ||  ||
 * 2 || 0.18 || nothing || nothing || 0.055 || 0.06 || 0.016 ||
 * 2 || 0.2 || nothing || nothing || 0.055 || 0.06 || 0.026 ||
 * 2 || 0.24 || nothing || nothing || 0.055 || 0.06 || 0.031 ||
 * 2 || 0.28 || nothing || nothing || 0.055 || 0.06 || 0.033 ||
 * 2 || 0.32 || nothing || nothing || 0.055 || 0.06 || 0.035 ||
 * 2 || 0.36 || nothing || nothing || 0.055 || 0.06 || 0.036 ||
 * 2 || 0.40 || nothing || nothing || 0.055 || 0.06 || 0.037 ||
 * 2 || 0.44 || nothing || nothing || 0.055 || 0.06 || 0.036 ||
 * 2 || 0.5 || nothing || nothing || 0.055 || 0.06 || 0.037 ||
 * 2 || 0.6 || nothing || nothing || 0.055 || 0.06 || 0.04 ||
 * 2 || 0.7 || nothing || nothing || 0.055 || 0.06 || 0.037 ||
 * 2 || 0.8 || nothing || nothing || 0.055 || 0.06 || 0.036 ||
 * 2 || 3 || Crack || Crack || 0.055 || 0.06 || 0.045 ||
 * 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.

W = Fd
 * W (J) || F (N) || D (m) ||
 * .106 || 6.625 || .016 ||
 * .118 || 4.54 || .026 ||
 * .141 || 4.55 || .031 ||
 * .165 || 5 || .033 ||
 * .188 || 5.37 || .035 ||
 * .212 || 5.89 || .036 ||
 * .235 || 6.35 || .037 ||
 * .259 || 7.19 || .036 ||
 * .294 || 7.95 || .037 ||
 * .353 || 8.825 || .04 ||
 * .412 || 11.14 || .037 ||
 * 1.764 || 39.2 || .045 ||

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? A human head. The dash board of a car. An air bag. Define the terms: Kinetic Energy and Work Energy an object in motion has The exertion of force on an object What factors determine an object's kinetic energy? Mass and Velocity When work is done on an object, what is the effect on the object's kinetic energy? If the work speeds the object up then it increases its KE and if it slows it down then it decreases it. How does the force needed to stop a moving object depend on the distance the force acts? The object has a KE which needs to be countered by work. Work is a certain amount force applied on an object until it stops. The longer it has to stop the object the less force it needs. What difference does a soft landing area make on a passenger during a collision? It makes it a lot softer and allows the object more distance to stop so its safer. How does a cushion reduce the force needed to stop a passenger? It allows the object more distance to stop in and thus a softer force acting on it. What does the law of conservation of energy have to do with this? The energy from the moving object is transferred into the cushion and thus it needs to be able to have a long distance so the force isn't as great and thus the impact is less.
 * Questions:**

· 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. Because all of your energy from your forward momentum needs to be counter acted by something to stop you, a lot of force needs to be applied. Because airbags can increase the distance you slow down over they decrease the force.
 * Conclusion:**

· Explain at least 1 cause of experimental error. Be sure you describe a specific reason. Flour and eggs don't equal skull and dashboard. This can't accurately tell us how effective airbags are because we aren't using skulls, dashboards, and airbags. · 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?) Do the same test (how fast a head with be seriously injured at without and airbag and then how much faster it can go with an airbag) with bones, airbags, and dashboards.

Chapter 3 - Section 5
__Momentum: Quantity of motion__ described by the product of mass and velocity. p = m x v Increase momentum: Large mass and small velocity, small mass and large velocity, large mass and large velocity

__**Physics To Go**__ 1) The automobile that has more momentum due to its velocity would push the stopped car forward so it gain velocity to the speed it was going. The already-moving car would stop. 4) They want heavier men, because they have a higher mass. The higher the momentum, the stronger and more forceful it will be in a collision (tackle) with a lighter player. The smaller guys don't have much of an impact on the bigger guys. 5) In a head on collision, the automobile with less momentum would get knocked backward. 6) P = mv 1000(10) = 10000 kg(m/s) 10000=10000v v = 1 m/s

Chapter 3 - Section 6

 * __Investigate__**

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). Two carts Tracks Velocity detector

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) ||
 * 0.505 || 0.489 || 0.34 || 0 || 0.994 || 0.18 ||
 * 0.755 || 0.489 || 0.41 || 0 || 1.244 || 0.25 ||
 * 1.003 || 0.489 || 0.39 || 0 || 1.492 || 0.28 ||
 * 0.505 || 0.739 || 0.42 || 0 || 1.244 || 0.2 ||
 * 1.005 || 0.949 || 0.52 || 0 || 1.954 || 0.29 ||

Calculations: Show equation(s), numbers plugged in, and answer with correct units. Add columns in your data table to include these results.

Find the initial momentum of the bullet cart for each trial. p=mv Find the initial momentum of the target cart for each trial. p=mv Find the sum of the initial momentum of the two carts for each trial. Momentum of both = momentum of bullet cart + momentum of target cart
 * || mass(kg) || velocity(m/s) || momentum(kg*m/s) ||
 * trial 1 || .505 || .34 || .1717 ||
 * trial 2 || .755 || .41 || .3096 ||
 * trial 3 || 1.003 || .39 || .3912 ||
 * trial 4 || .505 || .42 || .2121 ||
 * trial 5 || 1.005 || .52 || .5226 ||
 * || mass(kg) || velocity(m/s) || momentum(kg*m/s) ||
 * trial 1 || .489 || 0 || 0 ||
 * trial 2 || .489 || 0 || 0 ||
 * trial 3 || .489 || 0 || 0 ||
 * trial 4 || .739 || 0 || 0 ||
 * trial 5 || .949 || 0 || 0 ||

Find the final momentum of the combined carts for each trial. p=mv
 * || momentum of bullet (kg*m/s) || momentum of target (kg*m/s) || momentum of the two combined(kg*m/s) ||
 * trial 1 || .1717 || 0 || .1717 ||
 * trial 2 || .3096 || 0 || .3096 ||
 * trial 3 || .3912 || 0 || .3912 ||
 * trial 4 || .2121 || 0 || .2121 ||
 * trial 5 || .5226 || 0 || .5226 ||
 * || mass(kg) || velocity(m/s) || momentum(kg*m/s) ||
 * trial 1 || .994 || .18 || .1789 ||
 * trial 2 || 1.224 || .25 || .306 ||
 * trial 3 || 1.492 || .28 || .4178 ||
 * trial 4 || 1.244 || .2 || .2488 ||
 * trial 5 || 1.954 || .29 || .5667 ||

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

Compare the initial momenta (calc 3) to the final momentum (calc 4). (Allow for minor variations due to uncertainties of measurement.) All of them are very similar. They vary slightly because of small amounts of friction in that split second and faulty measurements. List the 6 types of collisions (top of page 312) and a brief description. Type 1: A moving object hits a non-moving object and they move together at the same speed Type 2: Two objects get sprung away from each other Type 3: A moving object hits a non-moving object and transfers all of its momentum to the stationary one Type 4: A moving object hits a stationary one and they bounce off at different speeds Type 5: Two objects hit one another and go off at differing speeds Type 6: Two objects hit and move at the same speed Which types of collisions are definitely inelastic? How do you know? Types 2, 4, and 5 because they involve a change in KE Which types of collisions are definitely elastic? How do you know? Types 1, 3, and 6 because they don't have a change in KE Define the law of conservation of momentum. During a collision of objects the momentum stays the same throughout the system. If objects are of different masses when the momentum is converted then the velocities will adjust accordingly. 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. The cue ball gets hit in quickly and transfers all of its momentum to the first ball which then passes it through all the touching balls. Their velocities are then slower as a result of the momentum being shared through all of the balls.

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. The push may not have a completely constant force, it's more accurate if for each push the same amount of force is applied. · 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?)


 * __Physics To Go__**

2) X--> <--X <--XX--> 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 total momentum after the collision = 0.

3) mvi + m2vi2 = mvf + m2vf2 100vi+100vi = 100(4) + 100(4) 200vi=800 vi= 4 m/s

5) After they collide, vehicle B gains momentum (the 4000 kg(m/s) that vehicle A lost. The change in momentum is zero because although A loses momentum, it is transferred to B.

6) mvi + m2vi2 = mvf + m2vf (200kg)(3m/s) + (200kg)(2m/s) = 200Vf + 200Vf 1000 = 400 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 7.775 m/s = Vf

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

Chapter 3 - Section 7
__**Physics To Go**__ 4) Bending your knees increases the distance in which you slow down and decreases the force applied on your legs 6a) p=mv p=1200(10) p=12,000 kg(m/s) -12,000 kg(m/s) to stop it 6b) p=mv p=1200(5) p=6,000 kg(m/s) at 5 m/s 12,000-6,000=6,000 kg(m/s) to bring to 5 m/s 7a) J = F(t) J = 10,000(1.2) J= 12,000 7b) J=p F(t) = m(__/\__v) 12,000=1200(__/\__v) 10 m/s= __/\__v 8) J = p F(t) = mv F (.1) = 1500(5) F = 75,000 N 10) The area is bigger, therefore the impulse is bigger. The first one is more dangerous because it has a larger spike.