Ch3_OringerR

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 * Ross Oringer Chapter 3 Wikilog**

Chapter 3- Section 1
I see a car completely wrecked in really bad crash, as seen the front hood is destroyed and the air bags have popped up. It ran into a wall at a great speed as seen in the damage. It is in a test crash facility. The teddy bear shows the parabola shape from the force. The back of the car has something attached. When it hit the wall, everything scatters.
 * What Do You See?**

Protection is key when involved in transportation. If riding a bike, one should wear a helmet because it will protect any major head injuries if a fall were to occur. If skating, wear wrist and knee pads to protect broken bones. Lastly, when in a car or automobile, wear a seat belt to stay in the seat and not go flying out the window.
 * What Do You Think?**

1/18/11 http://www.uppermichiganssource.com/news/story.aspx?id=56797 On January 15th, 2011, a fatal car crash occurred in Marquette. Due to bad conditions with slick snow and some ice, a car was damaged. The 1999 Dodge Caravan had three passengers in it. It lost control when crossing a center line, striking against a guard rail, and smashed right into a 2005 Chrysler Pacifica. The car received major damage and the passengers had to extricated. The major conditions were snow, and alcohol was not a factor.
 * Car Crash News Story**

1/19/11
 * Investigation **

a) I think my score is pretty representative of what I know. I thought the questions were a little misleading, and I over-thought most of them. I scored in the novice analyst category.
 * Part I:**
 * Part II:**

(yes/no) ||= New Cars (1,2,3) || and not allowing movement (inside of car) ||= no ||= 1 || move back and forward, lowers the number of whiplash injuries ||= no ||= 1 || pops up to prevent one from a serious injury of banging into the car ||= no ||= 1 || gets too close to another object, warning the driver ||= no ||= 3 || to absorb energy of crash; front of car ||= no ||= 2 || away from the head area to the legs, resisting side penetration ||= no ||= 2 || having to stop short, preventing skidding ||= no ||= 2 ||
 * Part III:**
 * = ** Safety features ** ||= Means of protection ||= Pre-1960 cars
 * = seat belt ||= keeps the person in seat
 * = head restraints ||= allow the back of the seat and headrest to
 * = front airbags ||= when a crash occurs, the air bag
 * = back up sensing system ||= sensor in the rear sensing when the vehicle
 * = front crumple zones ||= created to crumple in predetermined patterns
 * = rear crumple zones ||= (see above) but for the rear of the car ||= no ||= 2 ||
 * = side-impact beams in doors ||= deflect the force of a side-impact collision
 * = shoulder belts for all seats ||= keeps passenger in seat during collision ||= no ||= 1 ||
 * = anti-lock braking systems (ABS) ||= eliminate the need to pump brakes when
 * = tempered shatterproof glass ||= help prevent cuts ||= yes ||= 1 ||
 * = side airbags ||= protects head and torso ||= no ||= 2 ||
 * = turn signals ||= warn drivers of next turn ||= yes ||= 1 ||
 * = electronic stability control ||= help resist rollovers ||= no ||= 2/3 ||
 * = energy-absorbing collapsible steering column ||= prevents chest trauma ||= no ||= 1 ||

1/19/11 **Summary**: Vehicle Safety. Accidents can always occur. Governments and manufacturers of cars make vehicles safer. If you are in an accident in a safer vehicle, injury is limited. Pedestrians can get hit by a moving automobile. Ralph Nader, attorney and political activist, wrote //Unsafe at Any Speed.// It touches base on the problems of not wearing a seat belt, having hard chrome dashboards, and solid steering columns. The increase in fatal 4WD crashes could be due to growing number of kilometers traveled. Also, some drivers increase speed under the impression that the safety features will protect them.
 * Physics Talk **

1. Seat belts, back up sensing systems, and front air bags are improvements made on car manufacturers that increase safety in automobiles. 2. The increase in fatal 4WD crashes could be due to growing number of kilometers traveled. Also, some drivers increase speed under the impression that the safety features will protect them.
 * Checking Up Questions **

1/19/11 1.Front Airbags: **F**; Side Airbags: **S**; ABS: **T, S, F**; Back Up Sensing System: **R**; Crash Resistant Door Pillars: **S**; Front Crumple Zone: **F**; Rear Crumple Zone: **R**; Impact Absorbing Dashboard: **F**; Impact Absorbing Armrests: **S**; Traction Control: **T** 2. List of safety features for bicycling: helmet, knee pads, elbow pads, gloves, long pants, sneakers, hand signals 3. List of safety features for in-line skating: helmet, knee/elbow pads, wrist guards, comfortable-fitting roller skates, stopper on back 4. List of safety features for skateboarding: helmet, knee pads, elbow pads, wrist guards, sneakers
 * Physics To Go **

1/19/11 Accidents do occur, but devices are made for a reason to create safety. Cars have many devices and techniques created by engineers to prevent major damage in an accident in a car. The most effective safety device is definitely the seat belt because it is the most common, and most looked upon. The first thing that everyone does when entering a car is putting on the seat belt. It is very simple to use, and it is very safe by keeping a person in tact if a car accident were to happen. Actions like goofing around when driving, drinking and driving, and any other distractions that can cause an accident are dangerous. Reaction time can't be affected by things like this. Just by focusing on the road is a good start.
 * What Do You Think Now? **

Chapter 3- Section 2

 * Investigation**

> For a passenger involved in a car accident without a seatbelt, one can be injured or killed based upon the severity of the crash. Factors that affect the passenger's safety after a collision are if the passenger is capable of getting out of the car because the car may have flipped over. Also, the person could break bones or get glass in skin. A seatbelt in a racecar should keep the driver more intact because the driver can receive a much more dangerous injury due to the higher speeds traveled. With a seatbelt with many belts, the driver will definitely be able to stay in the seat, regardless of the severity of the crash and hopefully take away some of the injury.
 * 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.

Clay (person), ramp, textbooks, ribbons, and meter stick
 * Materials:** List any materials used and draw a labeled diagram of your set-up (alternatively, include a snapshot or video).

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.
 * Procedure** :

*Injury Height Without Seatbelt: .163 meters
 * Data and Observations**
 * **//Type of Seatbelt//** || //**Before Picture**// || //**After Picture**// || //**Description and Observations**// || //**Group**// ||
 * Thread

Brittany and Megan || ||  || The seatbelt holds him but the thread is so small so it puts too much pressure in small area which digs into his body. ||

(with seat belt still on)
 * Wire || [[image:activephysics-pvrhsd:Photo_11.jpg width="286" height="212" caption="Photo_11.jpg"]] || [[image:activephysics-pvrhsd:Photo_12.jpg width="285" height="211" caption="Photo_12.jpg"]]
 * Wire || [[image:activephysics-pvrhsd:Photo_11.jpg width="286" height="212" caption="Photo_11.jpg"]] || [[image:activephysics-pvrhsd:Photo_12.jpg width="285" height="211" caption="Photo_12.jpg"]]

(after removal of seat belt) || The clay passenger suffered cuts as a result of the narrow wire. When the cart plunged forward, he moved forward as well, pushing against his wire restraint. We observed lacerations to his shoulder and legs. || Andy and Amanda || the slant, he was in good condition and the ribbon was a decently sturdy seatbelt. After released down the slant the seatbelt restricted the person from falling out of the car. The damage wasn't very severe, he might have went through the windshield. Only a broken arm and maybe some injuries on the back/neck. Overall the seatbelt protected the clay person from death but no serious injuries. || 2 ||
 * String || [[image:activephysics-pvrhsd:beforeclayman!.jpg width="320" height="240" caption="beforeclayman!.jpg"]] || [[image:activephysics-pvrhsd:afterclaymannn.jpg width="320" height="240" caption="afterclaymannn.jpg"]] || The clay man was forced forward and caused indentations on the legs. He could have been forced forward because the string was not secure enough on the clay man. || Nicole and Courtney ||
 * Yarn || [[image:activephysics-pvrhsd:Photo_on_2011-01-31_at_14.36.jpg width="300" height="228" caption="Photo_on_2011-01-31_at_14.36.jpg"]] || [[image:activephysics-pvrhsd:Photo_on_2011-01-31_at_14.37.jpg width="309" height="235" caption="Photo_on_2011-01-31_at_14.37.jpg"]] || The little clay man was sent flying down the incline with a two-point seatbelt made of yarn around his waist and across his body and shoudler, and crashed into the end, without significant injury. No cuts could be seen from the force of the yarn on the man and no body parts were missing or out of place. The cart hit the end of the track and the little clay man did not move sitting in place where I had placed him on the cart. || 4 ||
 * Ribbon || [[image:activephysics-pvrhsd:before.png width="184" height="201" caption="before.png"]] || [[image:activephysics-pvrhsd:after.png width="373" height="142" caption="after.png"]] || Before we let our clay person go down
 * Rubber Bands ||  ||   ||   ||
 * Tape || [[image:activephysics-pvrhsd:tapeseatbeltan.jpg width="331" height="249" caption="tapeseatbeltan.jpg"]] || [[image:activephysics-pvrhsd:afteranseat.jpg width="321" height="241" caption="afteranseat.jpg"]] || The clay model was sent down the incline/ramp with a seat-belt made out of tape. The tape was wrapped around his waist and than pulled over his shoulder. The seat-belt allowed the clay model to go down the incline without ending up out of the cart and with significant injuries. The clay model was still held in by the seat-belt by the end of the trial, so in all the tape seat belt worked. ||


 * //*Read the Physics Talk p268 - 271 before answering the following questions. *// **
 * Questions**:
 * 1. Define the terms: inertia, force and pressure.** Inertia is the natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line. Force is an interaction between two objects which can result in an acceleration of one or both. Pressure is the force per area where the force is normal and directed perpendicular to the surface, measured in N/m^2 or Pa.
 * 2. In the collision, the car stops abruptly. What happens to the “passenger”?** In a collision, when a car stops abruptly, the passenger is moved forward rapidly, leading to dangerous consequences.
 * 3. What parts of your passenger were in greatest danger (most damaged)?** In reality, it depends on the location of the crash because the whole body is endangered. If contact on the side, you can get whip lash or whacked in the side of the body. If rear or head on, you can go through the windshield. The heart and brain keep moving. The body wall exerts the force that brings the organs to rest.
 * 4. What does Newton’s first law have to do with this?** Newton's 1st law states that an object in motion or rest will remain in motion or rest unless acted upon by an unbalanced force. This greatly embodies a car crash scenario.
 * 5. What materials were most effective as seat belts? Why?** The most effective seat belts were the ribbon and yarn because they are relatively thick/strong materials that can hold their own. They are not weak and elastic and can cause trouble.
 * 6. Use Newton's first law of motion to describe the three collisions.** First, the car hits the pole & the pole exerts a force that makes the car stop. Second, the car stops and the body keeps moving. The seat belt goes against this or anything that is in front of you. Yet, the car exerts a force that makes the body stop its motion forward. Third, the body stops, but the heart, brain, and other organs keep moving. The body wall gives off a force that makes the body stop. The ligaments and tendons can break or snap, and the organs can smash into the cavity that much harder, creating internal bleeding.
 * 7. Why does a broad band of material work better as a seat belt than a narrow wire?** The broad band of material works better than a narrow wire because it is thick and strong. Also, the force is spread out over a much larger area of contact.


 * 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.** In a car crash, the moving vehicle is hit with force by another vehicle, causing an opposite reaction. An object in motion will remain in motion unless acted upon by an unbalanced force. The car that is struck in an accident is stopped by another car. Seat belts are important to reduce the severity of the accident by keeping the passenger in the seat. A seat belt must be tight but comfortable to the person's body, securing them in the seat. The material must be broad, there must be low pressure, and the fabric shouldn't have much stretch. The ribbon used in my investigation was a thicker material and was wide, keeping the clay man out of death. It wasn't the best, but it worked. Race car drivers who drive at higher velocities need tighter and secure belts because in the case of an accident, consequences could be much more severe.
 * Explain at least 1 cause of experimental error. Be sure you describe a specific reason.** The clay man could have been sticking to the car because clay can mold on to other objects. Although, the clay man did fall off. Also, the ribbon could have been wrapped tighter around the person as well. Also, the slope of the ramp was not an exact measurement, but good enough to get results.
 * 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?)** I would change the passenger (material of object) because it was a clear advantage for some people. Also, the ramp should have been set at the exact same height for all people to ensure that every body could compare their results for the different material seat belts. Some people stacked more books than others under the ramps for different slopes.

Chapter 3- Section 3

 * Investigate X3: Energy and Air Bags**


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


 * Hypothesis:** An air bag is important in order to make sure that one's head doesn't go through a windshield, protecting serious damage. The air bag is the opposite reaction that stops the person in motion from flying through the windshield. When a driver is in an accident, the air bag is timed with the collision and protects the person from death, stopping the forward motion of the person in the accident.


 * Materials:** egg, bowl of flour, bag for egg, ruler, meter stick, weight scale

**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 length of your egg #1. Measure the mass of your egg. Record this information. // 5.5 cm; .058 kg // 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 flour and place the bowl inside of the box lid. // // 7. Measure the length of your egg #2. Measure the mass of your egg. Record this information. // .057 kg; 5 cm // 8. Drop the egg from the smash height (Step 5). 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. //
 * Procedure:**

//**Data and observations:** Add more columns/rows as needed.// (J) ||= W (J) ||= Force (N) ||
 * = **Egg #** ||= **Drop Height** ||= **Cracked or Smashed?** ||= **Description and Observations** ||= GPE
 * = 1 ||= 2 cm ||= small crack ||= We heard the crack, but it was almost invisible and very small. ||= .01 ||= .01 ||=  ||
 * = 1 ||= 4 cm ||= crack ||= Slight crack, and the same crack expanded. The bottom of the egg has a star shaped crack. ||= .02 ||= .02 ||=  ||
 * = 1 ||= 6 cm ||= crack ||= Now, the cracks combined it is dented. ||= .03 ||= .03 ||=  ||
 * = 1 ||= 8 cm ||= crack ||= The dent and the crack slightly increased ||= .05 ||= .05 ||=  ||
 * = 1 ||= 10 cm ||= crack ||= The crack is growing up the egg, and the yolk is more visible ||= .06 ||= .06 ||=  ||
 * = 1 ||= 12 cm ||= crack ||= Yolk is beginning to come out and crack increases ||= .07 ||= .07 ||=  ||
 * = 1 ||= 14 cm ||= crack ||= It has dented more and its almost flat at bottom. Yolk is coming out more. ||= .08 ||= .08 ||=  ||
 * = 1 ||= 16 cm ||= crack ||= Bottom is flat and yolk is going to fall out. ||= .09 ||= .09 ||=  ||
 * = 1 ||= 18 cm ||= crack ||= The sides are opening now and it is smooshed all over the bottom. ||= .10 ||= .10 ||=  ||
 * = 1 ||= 20 cm ||= crack ||= One whole side is completely cracked and the juice is flowing out. ||= .11 ||= .11 ||=  ||
 * = 1 ||= 22 cm ||= smashed ||= The yolk fell out. 1.5 centimeters were damaged from the 5.5 cm. ||= .12 ||= .12 ||=  ||
 * = 2 ||= 22 cm ||= none ||= The dent size is 1 cm and no crack. ||= .122 ||= .122 ||= 12.2 ||
 * = 2 ||= 32 cm ||= none ||= The dent size is now 1.5 cm. ||= .179 ||= .179 ||= 11.9 ||
 * = 2 ||= 42 cm ||= none ||= The dent size is 1.8 cm. ||= .234 ||= .234 ||= 13 ||
 * = 2 ||= 52 cm ||= none ||= The dent size is 2 cm. ||= .290 ||= .290 ||= 14.5 ||
 * = 2 ||= 62 cm ||= none ||= The dent size is 2.5 cm. ||= .346 ||= .346 ||= 13.84 ||
 * = 2 ||= 72 cm ||= none ||= The dent size is 3 cm. ||= .402 ||= .402 ||= 13.4 ||
 * = 2 ||= 82 cm ||= none ||= The dent size is 3 cm. ||= .458 ||= .458 ||= 15.3 ||
 * = 2 ||= 92 cm ||= none ||= The dent size is 3 cm again. ||= .513 ||= .513 ||= 17.1 ||
 * = 2 ||= 102 cm ||= none ||= The dent size is 3 cm. ||= .569 ||= .559 ||= 18.6 ||
 * = 2 ||= 200 cm ||= smashed ||= We missed the target and the egg smashed. ||=  ||=   ||=   ||
 * = 2 ||= 200 cm ||= smashed ||= We missed the target and the egg smashed. ||=  ||=   ||=   ||


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

GPE=mgh =(.058)(9.8)(.02) =.01J
 * SAMPLE CALCULATIONS**
 * What is the gravitational potential energy in each trial? GPE=mgh**

W=GPE W=(.058)(9.8)(.02) W=.01J
 * How much work is done in each trial? W=GPE**

W=F*d .122=F*(.01) F=12.2N
 * How much force was used to stop the egg in each case of steps 5, 8 and 9? W=F*d**

** *Read the Physics Talk p279 - 287 before answering the following questions. * ** The egg represents the person traveling in the car with constant motion. Eventually, the person will crash, and the egg hitting the table is the crash. The table is the tough windshield and dashboard located in front of the driver. The flour represnts the cushions/air bags that can prevent damage in a crash. KE=1/2mv^2. Kinetic energy is the energy possessed by a moving object. Work=Force times distance. Work is the force applied over a certain distance. Factors that determine an objects kinetic energy are the mass and the velocity becasue those are components of the equation KE=1/2mv^2. Work can be responsible for either increasing or decreasing the kinetic energy. This depends upon the direction the object is moving. If the work is moving with the object, it can increase it. If acting in an opposite direction stopping the object, it decreases kinetic energy. The object stopping the moving object is required work. Work is force times distance. The less the distance, the greater the force. The work done on a soft landing area decreases the kinetic energy of the object. The energy of the soft landing area increases. The soft landing area also decreases the chances of more damage. The cushions apply padding and more room for the person to go through. Alongside providing protection, it increases the distance for the person to stop and make contact during the accident. The stopping distance is greater. And the force required to stop the person decreases. Newton's first law states that an object in motion/rest stays in motion/rest unless an unbalanced force acts upon it. The person is the object in motion and airbag would be the unbalanced force halting the person from going through the windshield and getting injured.
 * 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 flour represent? **
 * 2. Define the terms: Kinetic Energy and Work. **
 * 3. What factors determine an object's kinetic energy? **
 * 4. When work is done on an object, what is the effect on the object's kinetic energy? **
 * 5. How does the force needed to stop a moving object depend on the distance the force acts? **
 * 6. What difference does a soft landing area make on a passenger during a collision? **
 * 7. How does a cushion reduce the force needed to stop a passenger? **
 * 8. What does the law of conservation of energy have to do with this? **

A person in a crash stays in motion unless an unbalanced force is acted upon it. In this case, the unbalanced force would be the dashboard and windshield located in front of the car. These two things would do work on the person during the crash to stop the person. The distance between the driver and the dashboard isn't great, and a crash would cause great damage. The airbags increase the distance of the driver when launched forward so the damage is less severe. In substitute of a car crash, the egg is like the driver. The flour is the airbag and the table is the dashboard or windshield. · **Explain at least 1 cause of experimental error. Be sure you describe a specific reason.** Experimental could be found in many ways. When determining the dropping distance, measurements are not exact at all. The size of the egg also is not exact. The flour being spread out in the bowl is not equal all around, because there can be more flour in different parts. Measuring the distance size of the dent also isn't exact. · **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?)** The size of the bowl with the flour was pretty small. If the bowl was set in a larger area, where the flour is more evenly spread out and the egg has more room to land in it, than results could vary. The position is difficult to change, but maybe if more eggs were used to test the smash height, it can ensure that results are correct. Having more test materials can improve results so you gain more heights that can be even.
 * 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. **

Chapter 3- Section 5
2/10/11 1. The car with a higher velocity has greater momentum. That car would push the car in rest forward and this car would gain the same speed. The car that collided with the car at rest will come to rest. 4. Football teams prefer offensive and defensive linemen who weigh 140 kg have a high mass. In the equation of momentum (p=mv), the higher mass can match up with a small velocity have greater momentum. With the momentum, the linemen can push his opponent back and create time for the quarterback. Also, the linemen doesn't necessarily need speed. 5. The one with more momentum will over power. In a head on collision, the car with the less velocity (momentum) would get moved backwards because the force of the car with greater momentum is more powerful. 6. p=mv 1000(10)=10,000kg m/s 10,000=10,000(v) v= 1 m/s
 * PTG **

Chapter 3- Section 6

 * Investigate X6: Momentum and Inelastic Collisions **


 * Objective**: What physics principles do the traffic-accident investigators use to "reconstruct" the accident?


 * Materials**: two carts, motion sensor, track, ruler, computers (Data Studio)


 * 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)** || **Initial Momentum**
 * kg m/s** || **Final Momentum**
 * kg m/s** ||
 * .256 || .257 || .65 || 0 || .513 || .36 || .1664 || .1846 ||
 * .756 || .257 || .69 || 0 || 1.013 || .34 || .5216 || .3444 ||
 * .256 || .757 || .59 || 0 || 1.013 || .19 || .1510 || .1924 ||
 * 1.256 || .257 || 1.49 || 0 || 1.513 || .69 || 1.871 || 1.043 ||
 * .256 || 1.257 || .73 || 0 || 1.513 || .22 || .187 || .333 ||


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

Pi=mv =(.256kg)(.65m/s) =.1664 kg m/s
 * 1. Find the initial momentum of the bullet cart for each trial.**

Pi=mv =(.257kg)(0 m/s) =0 kg m/s
 * 2. Find the initial momentum of the target cart for each trial.**

0 + .1664= .1664 kg m/s
 * 3. Find the sum of the initial momenta of the two carts for each trial.**

Pf=mv =(.513kg)(.36 m/s) = .185 kg m/s
 * 4. Find the final momentum of the combined carts for each trial.**

** *Read the Physics Talk p312 - 315 before answering the following questions. * ** When looking at the data chart, for the most part, the initial and final momenta are very similar numbers. Of course, they can not be exact because of measurement uncertainties.
 * Questions:**
 * 1. Compare the initial momenta (calc 3) to the final momentum (calc 4). (Allow for minor variations due to uncertainties of measurement.)**
 * 2. List the 6 types of collisions (top of page 312) and a brief description.**
 * 1) A moving object hits a stationary object: both stick together and move together with the same velocity.
 * 2) Two stationary objects explode by the release of a spring between them and move off in opposing directions.
 * 3) A moving object hits a stationary object: the initially moving object comes to rest, and the object originally at rest moves off in the same velocity as the first object
 * 4) A moving object hits a stationary object, and both move off at different speeds.
 * 5) Two moving objects collide: both objects move at different speeds after hitting each other.
 * 6) Two moving objects stay together: move together at the same velocity

Types 1 and 6 of the crashes display this. Inelastic collisions occur when the objects don't move (bounce) off each other. Instead of bouncing off, they stay together. The velcro in the lab helped display this because velcro obviously helps them stick together. Types two, four, and five display elastic collisions. Elastic collisions are exact opposites to those that stick together. They cars would bounce off of each other. Before the collision, the total momentum is equal to the total momentum after they collide (if there are no outside forces acting on the collision). The momentum of all the balls right after the collision plus the momentum of the original cue ball are equal. Natural forces conserve the momentum. The momentum will stay the same, however, when the cue hits the rack, the objects may move in new directions and with new speeds, depending on where the cue hits.
 * 3. Which types of collisions are definitely inelastic? How do you know?**
 * 4. Which types of collisions are definitely elastic? How do you know?**
 * 5. Define the law of conservation of momentum.**
 * 6. 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.**

It is important that the investigators know the momentum and the mass of the cars. Therefore, before the collision, they can find the masses and (momentum) that occur after the collision. Conserve means to maintain. The vehicles are able to maintain the same momentum before & after a collision, as seen the similar results to the final and initial momenta in the data chart.
 * 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?**

The wheels on the cars that we used were not the best, and had difficulty rolling. Therefore, this could throw off our results. Also, the track was not fully flat because the motion sensor was located slightly under it, lifting it up. The motion sensor also could have been slightly tilted, and not gaining the best possible results. I would use better cars with more sturdy wheels. We were giving the plastic cars, and unfortunately, were not as good as the standard ones used in class. Also, we would make sure the track is perfectly flat on the table, and the motion sensor is perfectly in line with the motion of the cars in the experiment.
 * 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?) **