Chapter+Three

=**Amanda Steiger's ActivePhysics Wikilog**toc= =**Chapter 3**=

Section One
Prompt: How can you protect yourself from serious injury should an accident occur? Response: The first step would always be to purchase the safest automobile, bike, or other mode of personal transportation available to you. Reacting quickly and efficiently will decrease damage, as well as not veering to either side of your motion path.
 * What do you think?**

The article "A Tougher Car Safety Agency" discusses the need for larger provisions to automobile safety. A new bill, the Motor Vehicle Safety Act, would greatly aid the National Highway Traffic Safety Administration's identification of serious problems. Safety laws must be enforced, and safety features must be encouraged in more cars. The legislature demands the public be provided with information about defects, and urges drivers to report any experienced issues. ([])
 * Homework 1/18/11**

Results of Quia True/False "Quiz"
 * Investigate**

Rank: Assistant Analyst (12 points) I was not surprised at the results. I am fairly familiar with driving statistics, but not am not knowledgeable enough to be considered an "expert analyst."

(yes/no) ||= New Cars (1,2,3) || positioned so as to protect passengers from being flung against the vehicle's structure ||= no ||= 1 || the main force of an impact ||= no ||= 2 || the main force of an impact ||= no ||= 2 || vehicle from skidding if applied suddenly ||= no ||= 2 || positioned so as to protect passengers from being flung against the vehicle's structure ||= no ||= 2 || the rest of the steering mechanism ||= no ||= 1 || Governments and car companies try to work together to improve car safety conditions. With safer cars, drivers, passengers, and pedestrians all have a better chance at avoiding serious injury if an accident should occur. Engineers are involved in the process to help ensure the most up-to-date technology is being installed in modern vehicles. In 1965, the novel //Unsafe at Any Speed//, by political activist Ralph Nader, concentrated on the numerous problems and hazardous parts of cars. Since then, cars have been designed with safety in mind.
 * = Safety Features ||= Means of Protection ||= Pre-1960 Cars
 * = seat belt ||= a belt or strap securing a person to prevent injury ||= no ||= 1 ||
 * = head restraints ||= intended to reduce the severity of neck and head injuries ||= no ||= 1 ||
 * = front airbags ||= designed to inflate rapidly in the event of a collision and
 * = back up sensing system ||= allows to see in blind spots while backing up ||= no ||= 3 ||
 * = front crumple zones ||= designed to crumple easily in a crash and absorb
 * = rear crumple zones ||= designed to crumple easily in a crash and absorb
 * = side-impact beams in doors ||= resists side penetration ||= no ||= 2 ||
 * = shoulder belts for all seats ||= seat belt that passes over the shoulder and across the chest ||= no ||= 1 ||
 * = anti-lock braking systems (ABS) ||= designed so as to prevent the wheels from locking and the
 * = tempered shatterproof glass ||= "laminated" safety glass that holds together when shattered ||= yes ||= 1 ||
 * = side airbags ||= designed to inflate rapidly in the event of a collision and
 * = turn signals ||= a flashing light on a vehicle to show that it is about to change lanes or turn ||= yes ||= 3 ||
 * = electronic stability control ||= improves the safety of a vehicle's stability by detecting and minimizing skids ||= no ||= 3 ||
 * = energy-absorbing collapsible steering column ||= a shaft that connects the steering wheel of a vehicle to
 * Physics Talk: Vehicle Safety**

1. Manufacturers now install anti-lock brakes, airbags, and seat belts in most modern cars for safety reasons. 2. The increase in crashes is thought to be a result of the growing number of kilometers traveled by the 4WD vehicles, or the sense of false security luring drivers of 4WD cars into accidents.
 * Checking Up**

1. 2. Safety features that can be used with bicycling include: turn signals, wearing bright clothing, maintaining a constant, reasonable speed, and training wheels. 3. Safety features that can be used with in-line skating include: wearing protective pads, turn signals, and proper skates. 4. Safety features that can be used with skateboarding include: turn signals, wearing proper foot attire, maintaining a constant, reasonable speed, and protective pads.
 * Physics To Go**
 * Safety Feature || Designations ||
 * Seat Belts || F, R, S, T ||
 * Head Restraints || F, R ||
 * Front Airbags || F, R ||
 * Side Airbags || S ||
 * Shatterproof Glass || F, R, S, T ||
 * Front Crumple Zones || F ||
 * Back Crumple Zones || R ||
 * Anti-Lock Brakes || F, R, S, T ||
 * Side Impact Beams || S ||
 * Turn Signals || F, R, S, T ||

Prompt: How can you protect yourself from serious injury should an accident occur? Response: When shopping for a mode of transportation, be sure the one you purchase is the safest available. Always drive or ride cautiously, and remember to buckle your seat belt. Indicators and turn signals help avoid accidents.
 * What do you think now?**

**Section Two**
Prompt: Suppose you had to design a seat belt for a race car that can go 300 km/h (about 200 mi/h). How would it be different from one available on a passenger automobile? Response: I would design a seat belt with a large surface area, made of a durable, soft material.
 * What do you think?**

What happens to a passenger involved in a car accident without and with a seat belt? 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?
 * Investigate**

Materials used: Clay, ramp, cart, wire, meter stick

Data and observation: Injury height with no seat belt: .33m (33cm) (with seat belt still on)
 * //Type of Seat-Belt// || //Before Picture// || //After Picture// || //Description and Observations// || //Group// ||
 * Wire || [[image:Photo_11.jpg width="170" height="124"]] || [[image:Photo_12.jpg width="170" height="124"]]

(with seat belt removed) || 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 ||

Questions: 1. Define these 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 that can result in an acceleration of either or both objects. Pressure is force per area where the force is perpendicular to the surface. 2. In the collision, the car stops abruptly. What happens to the "passenger"? The passenger moved forward with the cart. 3. What parts of the passenger were in greatest danger (most damaged)? The passengers shoulders and legs were suffered the most injury. 4. What does Newton's first law have to do with this? The passenger continued to move after the cart had come to a stop. 5. What materials were effective as seat belts? Why? The broader, softer materials were more effective because they would not cut the passenger and gave a larger surface area for pressure. 6. Use Newton's first law of motion to describe the three collisions. The car hits the endstop and comes to a halt; the person hits their seat belt and stops moving; the body wall stops the person's organs. 7. Why does a a broad band of material work better as a seat belt than a narrow wire? A broad band of material works better as a seat belt because less pressure is placed on the passenger.

Conclusion: 1. 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 seat belt? What would you need to consider when designing a seat belt for a race car? Use specific observations from this investigation to support your answers to these questions. 2. Explain at least one cause of experimental error. Be sure you describe a specific reason. 3. 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?)

Newton's first law states that an object at rest will stay at rest, and an object in motion stays at motion in a straight line with constant speed unless acted upon by a net, external force. Newton's first law is sometimes called the law of inertia. Inertia is the natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line. Police men and insurance companies consider every accident to be comprised of three collisions. Force is an interaction between two objects that can result in an acceleration of either or both objects. Force that is spread out over a given area is called pressure. Pressure is defined as force per area where the force is normal (perpendicular) to the surface. Pressure is measured in newtons per meter squared or pascals (Pa).
 * Physics Talk: Seat Belts and Newton's First Law of Motion**

1. Newton's first law of motion explains that an object at rest will stay at rest, and an object in motion will stay in motion in a straight line path with constant speed until acted upon by an external force. 2. Inertia, the natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line, is present in the driver. Therefore, after the car has stopped moving, the driver continues to move in the direction the car would have kept going. 3. In the first collision, the force of the pole on the car is the external force that halts the car's motion path. In the second collision, the structure of the automobile exerts the force that brings the body to rest. In the third collision, the body wall exerts a force bringing the organs to rest. 4. Inertia is the natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line. The more mass an object has, the more inertia it has. This means that inertia and mass have a direct relationship. 5. When a thin wire was used, all of the force was concentrated onto a small area. By replacing the wire with a broader strip of material, you spread the force out over a much larger area of contact.
 * Checking Up**

Prompt: Suppose you had to design a seat belt for a race car that can go 300 km/h (about 200 mi/h). How would it be different from one available on a passenger automobile? Response: I would design a seat belt with a large surface area, made of a durable, soft material. The larger the surface area, the lesser the force applied on the driver's chest. A strong, softer material will absorb pressure better than a flimsy one. The seat belt would possess elastic qualities to prevent further damage to the internal organs in the third collision. Because the driver is moving so fast, accidents are likely, and so it is extremely important to give him or her the best protection possible.
 * What do you think now?**

1a. 10 N/m^2 1b. 50 N/m^2 1c. 2/3 N/m^2 1d. 250 N/m^2 2a. 17500 N/m^2 2b. 35000 N/m^2
 * Physics Plus**

1a. The brakes apply a force to stop the car. The interior of the car applies a force to stop the driver from moving. 1b. The accelerator applies a force to start the car. The interior of the car applies a force to get the driver moving. 1c. As a result of inertia, an object may continue to move after the car has stopped. 1d. The seat belt applies a force to restrict the passenger. 4. Three collisions are described in this section's Physics Talk. The first collision is the car hitting a pole. The force of the pole on the car stops the car. During the second collision, the car comes to a stop but the body continues to move. The body continues to move because of inertia. The interior of the car applies the force that brings the body to rest. The third and final collision occurs when the body stops, but the heart, brain, and other organs continue moving. The body wall exerts the force that brings the organs to rest. 6. Laws making seat belts mandatory are completely fair and beneficial. Seat belts are of no real inconvenience, and serve as a huge bodily protector. It's extremely important to buckle your own seat belt and make sure all passengers in your car have their seat belts buckled as well. 7a. He or she might claim the seat belt is uncomfortable and/or unnecessary. 7b. I would explain to him or her that the seat belt, though it may be uncomfortable, is extremely necessary. If we were to get into an accident, a seat belt could prevent serious injuries or death.
 * Physics To Go**

Pressure is equal to force over area. The pressure on the foot pedal must be equal to the pressure on the breaks. The area on the brakes is much greater than the area on the pedal, causing the force applied by the breaks to be much greater than the force applied by the driver's foot. Hence, the car comes to a halt. However, in the process, energy is conserved because the driver has to press a longer distance on the pedal for the break pads to move a smaller distance. The large force between the break pads and the break disc is sufficient to stop the car.
 * Extra Credit: Inquiring Further**

Here is a diagram depicting the sequence of events following the driver's foot exerting a force on the pedal:

Section Three
How does an air bag protect you during an accident?
 * Investigate**

Materials used: egg, ziploc bag, meter stick, flour, box lid,

Data and observation: Mass of egg 1: 0.059kg Height of egg 1: 7cm Mass of egg 2: 0.061kg Height of egg 2: 5cm //(cm)// || //Cracked or smashed?// || //Description and observations// || //Length of egg in flour// //(cm)// || //Length of egg outside flour// //(cm)// || //GPE// //(j)// || //W// //(j)// || //F// //(j)// || Calculations:
 * //Egg Number// || //Drop Height//
 * 1 || 2 || Cracked || Small fractures in egg shell ||  ||   ||   ||   ||   ||
 * 1 || 4 || Cracked || Small fractures in egg shell ||  ||   ||   ||   ||   ||
 * 1 || 6 || Cracked || Small fractures in egg shell ||  ||   ||   ||   ||   ||
 * 1 || 8 || Cracked || Small fractures in egg shell ||  ||   ||   ||   ||   ||
 * 1 || 10 || Cracked || Small fractures in egg shell; peeling observed ||  ||   ||   ||   ||   ||
 * 1 || 12 || Cracked || First sign of yolk ||  ||   ||   ||   ||   ||
 * 1 || 14 || Cracked || Bottom of shell collapsed, egg-white released ||  ||   ||   ||   ||   ||
 * 1 || 16 || Cracked || Damaged continued, yolk visible ||  ||   ||   ||   ||   ||
 * 1 || 18 || Cracked || Fractures spread ||  ||   ||   ||   ||   ||
 * 1 || 20 || Cracked || Yolk is still contained ||  ||   ||   ||   ||   ||
 * 1 || 22 || Cracked || Most of egg-white released, yolk remains in shell ||  ||   ||   ||   ||   ||
 * 1 || 24 || Cracked || Yolk begins to leave shell, shell is separating ||  ||   ||   ||   ||   ||
 * 1 || 26 || Smashed || Yolk ||  ||   ||   ||   ||   ||
 * 2 || 26 || No damage || No visible damage || 2 || 3 ||  ||   ||   ||
 * 2 || 36 || No damage || No visible damage || 2.5 || 2.5 ||  ||   ||   ||
 * 2 || 46 || No damage || No visible damage || 3.5 || 1.5 ||  ||   ||   ||
 * 2 || 56 || No damage || No visible damage || 4.5 || 0.5 ||  ||   ||   ||
 * 2 || 66 || No damage || No visible damage || 4.75 || 0.25 ||  ||   ||   ||
 * 2 || 76 || No damage || No visible damage || 1.5 || 3.5 ||  ||   ||   ||
 * 2 || 86 || No damage || No visible damage || 3 || 2 ||  ||   ||   ||
 * 2 || 96 || No damage || No visible damage || 3 || 2 ||  ||   ||   ||
 * 2 || 106 || No damage || No visible damage || 3 || 2 ||  ||   ||   ||
 * 2 || 200 || No damage || No visible damage || 3 || 2 ||  ||   ||   ||

Questions:

Conclusions:

Section Six

 * Investigate**
 * //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)// ||
 * .257 || .5 || .62 || 0 ||  || .21 ||
 * 1.257 || 1.0 || .51 || 0 ||  || .26 ||
 * 1.75 || 1.0 || .60 || 0 ||  || .37 ||
 * 2.25 || .5 || .58 || 0 ||  || .45 ||
 * 1.25 || 1.5 || .62 || 0 ||  || .25 ||
 * 0.75 || 2.0 || .44 || 0 ||  || .13 ||