Chapter3-bkist

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Bryan Kist's Wikilog - Period (6) CP Physics - (E. Burns) - 2010

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=Chapter 3, Section 1=

What do you see- There is a car crashing into a big bag attached to barrier. The car is collapsing in the front because of the pressure from the barrier What do you think- You can protect yourself by wearing a helmet to absorb and redirect the shock from your head. Using a seat belt would stop you from getting flung from the car because you are in motion when you crash.

Investigate 2. I received a 11-15 and an Assistant Analyst, i was somewhat surprised because i was not sure about some of the answers facts that i got right



(yes/no) || New Cars (1,2,3) ||
 * Safety features || Means of protection || Pre-1960 cars
 * seat belts || keeps drivers inside of the car || no || 1 ||
 * head restraints || prevents whiplash || no || 1 ||
 * front airbags || cushions during a collision || no || 1 ||
 * back up sensing system || allows to see in blind spots || no || 3 ||
 * front crumple zones || increase collision distance || no || 1,2 ||
 * rear crumple zones || increase collision distance || no || 2 ||
 * side-impact beams in doors || resist side penetration || no || 2 ||
 * shoulder belts for all seats || keeps passengers in seats || no || 1 ||
 * anti-lock braking systems (ABS) || helps maintain control || no || 2 ||
 * tempered shatterproof glass || prevents cuts || yes || 1 ||
 * side airbags || protects head/torso || no || 2 ||
 * turn signals || warns other drivers || yes || 1 ||
 * electronic stability control || helps resist rollovers || no || 2,3 ||
 * collapsible steering column || prevents chest trauma || no || 1 ||

Physics talk - Vehicles are designed to help you stay safe during an accident - Engineers try to make vehicles safer for not only passengers but also pedestrians - Ralph Nader published several things that were important to have in a car to stay safe such as the seat belt and solid steering columns - Fatal crashes in 4WD vehicles increased by 85% between 1990 and 1998 - All fatal crashes have decreased between 1994 to 1998 by 25% - Vehicles with Anti-Lock brakes and 4WD should be safer than those without

Checking Up Questions 1. Vehicles have been made safer by putting in seatbelts, Anti=Lock braking systems, and 4 wheel drive. 2. Crashes in 4WD's have increased because there has been an increase in the Kilometers traveled by 4WD's.

Physics To Go 1. Head Restraints- F/R Front Air Bags- F/R/S Back Up Sensing System- None Front Crumple Zones- F Rear Crumple Zones- R  Side Impact Beams- S/T Tempered Shatter proof glass- F/R/S/T Side Airbags- S Electronic Stability Control- T  Collapsable Steering Column- F/R

2. elbow pads, Helmets, knee pads

3. Helmet, elbow pads, knee pads

4. Seatbelts, Head Restraints, front airbags, back up sensing system, front crumple zone, rear crumple zone, side impact beams, shoulder belts, ABS, Tempered Glass, Side airbags, turn signals, ESC, Collapsable Steering Column

What Do You Think Now - Ways that you can prevent injuries in accidents is to make sure that you follow all of the proper safety precautions before going on the roads and making sure your car is equipped the all of the safety features that you need. Some things that will not protect you during an accident such as not putting on your seatbelt or trying to brace yourself because there is not enough time.

**Investigate X2: Newton's FIrst Law and Seatbelts**

 * Objectives:**
 * What happens to a passenger involved in a car accident without and with a seat belt- If they did not have a seat belt they would fly forward, if they had a seat belt they would be stopped and not be ejected from the car.
 * What factors affect the passenger’s safety after a collision?- factors that play a roll in this are how much the seat belt extends, and how fast the car is traveling, or if the seat belt is locked in place.
 * How would a seat belt for a race car be different from one available on a regular car? - one in a race car would be much bigger and stronger because they are traveling at much faster speeds.


 * Hypothesis:** Respond to each of the above objectives fully.


 * 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: .12 m


 * **//Type of Seatbelt//** || //**Before Picture**// || //**After Picture**// || //**Description and Observations**// || //**Group**// ||
 * Thread ||  ||   ||   ||   ||
 * Wire ||  ||   ||   ||   ||
 * String ||  ||   ||   ||   ||
 * Yarn || [[image:Photo_88.jpg width="320" height="240"]] || [[image:Photo_89.jpg width="320" height="240"]] || The man was thrown from the cart because he kept moving, when we added the seat belt, it stopped him from being thrown from the cart but it dug into his chest because the pressure was to great. ||  ||
 * Ribbon ||  ||   ||   ||   ||
 * Rubber Bands ||  ||   ||   ||   ||

//** *Read the Physics Talk p268 - 271 before answering the following questions. * **// Questions:
 * 1) Define the terms: inertia, force and pressure. Inertia is a tendency to do nothing or to remain unchanged, Force is a energy applied to an object, pressure is the force per area
 * 2) In the collision, the car stops abruptly. What happens to the “passenger”?- they continue to move
 * 3) What parts of your passenger were in greatest danger (most damaged)?- their organs because they were stopped by the body cavity
 * 4) What does Newton’s first law have to do with this- just because the car is stopped, that does not mean the person is stopped
 * 5) What materials were most effective as seatbelts? Why? the ribbon because it takes a bigger force and spreads it out
 * 6) Use Newton's first law of motion to describe the three collisions. The car is stopped by the pole, then the person is stopped by the seat belt, and the persons organs are stopped by their body cavity.
 * 7) Why does a broad band of material work better as a seatbelt than a narrow wire? its spreads out the force applied on the person

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. - An object in motion, has a tendency to stay in motion unless acted on by an unequal force. A seat belt is important because it stops you from being thrown out of the car. Just because the car is stopped, that does not mean you are stopped. One observation was that we saw the thread starting to dig into the person, showing that they were still moving as the cart stopped.

· Explain at least 1 cause of experimental error. Be sure you describe a specific reason. - one source of experimental was that the person may have been attached to the cart because it was clay. · 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?) - one way i would make this lab better is by making the clay person frictionless eliminating him sticking to the cart.

=Section 3=

**Investigate X3: Energy and Air Bags**

 * Objective:**
 * How does an air bag protect you during an accident? it makes the impact of the crash less severe my making the impact distance longer there by lowering the force


 * Hypothesis:** Respond to the objective fully.


 * 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. //.055m // 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 vertially. 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** ||  ||
 * 1 || 2cm || nothing || nothing happened ||  ||
 * 1 || 4cm || cracked || very slightly cracked ||  ||
 * 1 || 6cm || cracked || more cracked, still no leaking ||  ||
 * 1 || 8cm || cracked || 1/3 cracked, no leaking ||  ||
 * 1 || 10cm || cracked || more cracked ||  ||
 * 1 || 12cm || cracked || even more cracked ||  ||
 * 1 || 14 || cracked || still no yolk ||  ||
 * 1 || 16 || cracked || white started to spill ||  ||
 * 1 || 22 || smashed || yolk was EVERYWHERE!!!!! ||  ||
 * 2 || 22 || nothing ||  ||   ||
 * 2 || 26 || nothing ||  ||   ||


 * 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) 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?

· 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?)
 * Conclusion:**

=Momentum= Momentum- is a quantity in motion described by the product of mass and velocity P= M*V

Large Mass+Small Velocity Small Mass+Large Velocity Large Mass+Large Velocity

Physics to go, 1,4,5,6

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)** ||


 * 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) List the 6 types of collisions (top of page 312) and a brief description.
 * 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.

· 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?)
 * Conclusion:**

==****Investigate 7: Impulse and the Crumple Zone**** ==

// Objective: A crumple zone is part of the body of a car that compresses during an impact. It absorbs the energy of the collision and lessens the force on the passengers. //
 * What are some of the factors that car designers and engineers must consider when designing a crumple zone as a safety feature?- how thick it must be or how much force it applies, and how much force it can absorb
 * What enables a passenger to survive a collision?- the fact that they do not stop immediately and the force is spread over a safe distance.
 * What does a Force vs. Time graph look like for a collision?- it immediately drops to 0 because the car is stopped and there is no more force
 * What would the Force vs. Time graph look like if the collision was more safe? - it would slowly drop to nothing so it would be spread out over a large distance and time.

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

//Procedure:// // 1. On the floor, place a ramp on a stand so that one end is raised 10-cm and the other end is 20 cm from the wall. // // 2. Place a block in the cart and attach a 2-cm piece of masking tape to the front of the block and down onto the cart. Place the cart at the top of the ramp and release it. Record your observations. // // 3. Design a crumple zone to protect the block from tipping over. You can use only the following materials: one sheet of paper, 30-cm tape, 2 rubber bands, and 30-cm of string. Record your design(s) and the changes you make to it in a data table. You may want to use the available technology (still pictures and video) to supplement your written descriptions. // // 4. Measure the mass of your cart with apparatus attached. // // 5. Once you have a functional design that you are happy with, you will bring it to the front of the room to test. You will allow your cart to crash into a force sensor in order to generate a force vs. time graph, while a motion detector will measure the speed of the cart. // // 6. Click the ∑ button to get the area of the F-t Graph. Click the smart tool to get the velocity of the cart before and after the collision. // // 7. Repeat 3 times. //


 * Data and observations:** Add more columns/row as needed.

**Calculations:** Show equation(s), numbers plugged in, and answer with correct units. Add columns in your data table to include these results. 1. Calculate the change in momentum for your cart. 2. Impulse is equal to the area of the F-t graph. What is the impulse experienced by your cart?

***Read the Physics Talk p324 - 329 before answering the following questions.** *

1. Define the following terms: velocity, acceleration, Newton’s second law of motion, and momentum, impulse. 2. What is a crumple zone? 3. Why is it safer to collide with a soft cushion than a hard surface? 4. What is the relationship between impulse and change in momentum? 5. How is the impulse-momentum relationship related to Newton’s second law? 6. What were the key features of your crumple zone and why were they important? 7. What happened to the area of the Force-time graph as we increased the speed of the cart? 8. What happened to the area of the Force-time graph when the collision was inelastic vs. elastic?
 * Questions:**

**Conclusion:** · What are some of the factors that car designers and engineers must consider when designing a crumple zone as a safety feature? Compare and contrast crumple zones and air bags. · 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?)

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