De La Salle University Dasmarias Cavite, Philippines

College of Science and Computer Studies

PRELIM ELGA PROJECT

Physics 1 Laboratory: Heat and Mechanics

Force and Survivability: Mortality rate of people in a car crash

Engr. Sulpicio Reyes

Garduque, Joshua D.

Guillermo, Janina Suzette C.

Guillermo, Josiah Gabe

Guingab, Karl Romney G.

Igros, Aljoie Rose G.

Jumarang, Jewel Joie C.

Larumbe, Jovet Emmanuel S.

MEB 22

SY: 2014 2015Force and Survivability: Mortality rate of people in a car crash

I. INTRODUCTION

COLLISION, NEWTONS LAWS, IMPULSE AND FRICTION

One of the problems that every country faces is the danger in the road. Car accidents deliberately happen. In line with this, Physics is quite related most especially the study of Kinematics, namely in car collisions. A collision is an event where momentum or kinetic energy is transferred from one object to another. Momentum (p) is the product of mass and velocity (p = mv).There are two general types of collisions in physics: elastic and inelastic. Inelastic collision occurs when two objects collide and do not bounce away from each other.

This is where momentum is conserved because the total momentum of both objects before and after the collision is the same. But the kinetic energy is not conserved it is because some of the kinetic energy is converted into sound, heat, and deformation of the objects.Another type of collision is an elastic collision occurs when the two objects "bounce" apart when they collide. Two rubber balls are a good example.

In this collision, both momentum and kinetic energy is conserved which means no energy was lost. Also the amount of force that causes an accident is largely dependent on Newtons second and third law. For every action, there is an equal and opposite reaction respectively. The Newtons First Law dictates that in the absence of external force, an object at rest remains at rest and an object in motion remains in motion with a constant velocity. This explains why passengers in cars are thrown about in a collision. The forces that are being applied to the car during a crash are not being directly applied to the passenger, the passenger will keep moving even if the car stopped moving. The speed that the passenger hits the interior of the vehicle is roughly equal to the speed of the vehicle before it comes to an abrupt stop.

Acceleration and deceleration also are a huge factor in physics which are related to the second law. This states that the acceleration of an object is directly proportional to the net force acting on it and is inversely proportional to its mass. In a car, the harder its body, the greater rate of acceleration or deceleration on the whole car. This means that a greater acceleration for the same mass results in greater force ( F=MA), which would mean passengers of the car would be subject to more violent jerking and might possible sustain more injury, even though the car would have less damage.While in cars with soft body, the car body would crumple up more and a slower rate of acceleration or deceleration on the whole for the car, resulting in less violent jerks of passengers, meaning less chance of injury.This would lead to death of the passengers. The third law is about the force exerted by object 1 onto object 2 is equal in magnitude and opposite in direction to the force exerted by object 2 onto object 1. The faster the initial crushing speed, the greater impact would be felt.

Mass is very important wherein of the mass of the passenger is very light, there would be a high possibility to get thrown away. For the ones with heavy weight, with greater mass, acceleration would be less following the rule applied F=ma.The use of seat belt or air bag does not only prevent the passenger from bouncing inside the vehicle but it also spreads the time that the decelerating force that is applied to the person. It does not harm the person but with a deceleration in such a short period of time, that one could be dangerous. Impulse is the term used to represent force over time.

Another factor that should be considered in car accidents is friction. It is the force that resists the motion when two objects are in contact.

This is the relation between the tires and the road. With soft tires, the better it breaks but the shorter time it lasts. On the other hand, with hard tires it is more efficient and better fuel economy.The level of friction that different materials exhibit is measured by the coefficient of friction. The formula is = f / N, where is the coefficient of friction, f is the amount of force that resists motion, and N is the normal force. Normal force is the force at which one surface is being pushed into another.

There are two types of friction namely kinetic and static. When two objects slide past each other, a small amount of force will result in no motion. The force of friction is greater than the applied force. This is static friction. If there is an application of a little more force, the object "breaks free" and slides. This is kinetic friction.

II. RESEARCH

A. REASONS FOR CAR ACCIDENTS AND STATISTICS

Based on statistics from thePhilippine National Police-HighwayPatrol Group (PNP-HPG),road accidents is one of the leading causes of death in the Philippines. In 2012, there is an average of 227 road accidents per day according to MMDA. On the other hand, the Cement Manufacturers Association of the Philippines(CeMAP) just held its2ndVehicle and Traffic Safety Conference, 20th of July 2013,at the SMX Convention Center. The event tackled road safety issues faced by trucking companies hired by CeMAP members.

The CeMAP invited keynote speakerDante Lantin, assistant secretary with theDepartment of Transportation and Communications, to give an update on the situation using data from 2012 gathered by the DOTC and concerned government agencies like the Land Transportation Office and the Metropolitan Manila Development Authority.Below are the lists of the records of what is happening on the road:13 million- Total driver's licenses issued7,463,393- Total motor vehicles registered270,000km- Total length of roads nationwide132,089- Violators of the Seatbelt Use Act90%- Motorcycle riders in Metro Manila that follow the Helmet Law90%- Motorcycle riders outside of Metro Manila that don't follow the Helmet Law79%- Road crash fatalities caused by driver error11%- Road crash fatalities caused by defective vehicles10%- Road crash fatalities caused by bad road conditions and ill-maintained roads16%- Road crashes caused by trucks in the first half of 201312%- Road crashes caused by trucks in 20127.5%- Percentage of the Road Users Tax collected annually that will be allotted for road safety measuresAs said by Lantin in the end of his presentation, "Our target by 2020 is to reduce by 50% the number of fatalities due to road crashes.In relation to these data, here are the causes of such accidents:

1. Drunk DrivingDriving in the influence of drugs and alcohol is the top cause of road accidents in the Philippines. Alcohol slows reflexes, weakens reasoning, and affects ones motor skills definitely unfit to drive. But despite government warnings and road accidents, drunken people still get behind the wheel.

2. Over speedingWith the adrenalin rush it is undeniable that drivers find exciting in over speeding. At the same time, it is about the carelessness of the driver, trying to show off sometimes and taking it as a joke not knowing that their lives are at risk.

3. Mechanical MalfunctionsMost of the time, drivers forget to check their cars before leaving. Every driver must check their engine if it is in good condition most especially in long drives.

4. Lost BrakesOne of the reasons and most overused excuses of road accidents by drivers are their brakes.

5. OvertakingOvertaking is when a driver goes ahead of another vehicle or vehicles in front of him. Accidents happen when the drivers miscalculate the moves of upcoming vehicles from other lanes. To avoid collision, maintaining the speed if think the car behind trying to overtake just let him get through you.

6. Abrupt ManeuversMost of the time, abrupt movements on the road are caused by avoiding other vehicles. Because of the threat of possibly hitting other vehicles or pedestrian, the driver chooses to do sudden maneuvers. Drivers must always put their attention to the road and always check through mirrors. Alertness and quick reflexes should be on drivers expertise.

7. Bad Turns & ReverseIts understandable that adjusting speed and direction quick is not easy. But, thats what signal lights are for. Make driving decisions as swift and wise as possible.

B. CAR ACCIDENT REPORTSCase 1: A local high school basketball star was seriously injured in a crash Sunday night.Josh Speidel, a standout player at Columbus North, was taken to Methodist in critical condition after a two vehicle crash just after 7:00 p.m. on US-31 near Bear Lane in Taylorsville. That's about 40 minutes south of downtown Indianapolis in Bartholomew County.A preliminary investigation shows 42-year-old Janell Foley of Columbus, Ind., had just exited off Interstate 65 and was driving southbound on US-31 when Speidel started driving onto US-31 from a side road on the west side driving 100 kph. The 18-year-old's car was hit on the driver's side. Rescue workers had to use the jaws of life to cut off the roof and door of his car to get him out.His passenger, 18-year-old Kaylee McCracken of Greenwood, was taken to the hospital but is expected to be okay.Foley was treated and released at the scene. Her two sons, ages 9 and 14, were not injured.First responders said Speidel suffered head trauma and internal injuries.He is committed to play at the University of Vermont.

Case 2: The Porsche carryingFast & Furiousstar Paul Walker was travelling approximately 145 km/h when it lost control on a suburban street and crashed, killing the actor and his friend, the Los Angeles County Sheriff said on Tuesday, concluding an almost four-month investigation."Investigators determined the cause of the fatal solo-vehicle collision was unsafe speed for the roadway conditions," Los Angeles County Sheriff Commander Mike Parker said in a statement.The sports car slammed into a light pole which had a speed limit sign of 45 mph (about 72km/h), killing Walker and Roger Rodals in a fiery wreck. Parker said the 2005 model-year high-powered sports car had been modified to increase its horsepower.Investigators calculated that Rodas was driving between 130 km/h and 151 km/h when his 2005 Porsche Carrera GT began to drift as it lost control after coming out of a curve.

C. TWO-CARS IN TWO DIMENSIONAL COLLISION

Inelastic Collision

Collisions between objects are governed by laws of momentum and energy. When a collision occurs in an isolated system, the total momentum of the system of objects is conserved. Provided that there are no net external forces acting upon the objects, the momentum of all objects before the collision equals the momentum of all objects after the collision. If there are only two objects involved in the collision, then the momentum change of the individual objects are equal in magnitude and opposite in direction.

Certain collisions are referred to as elastic collisions. Elastic collisions are collisions in which both momentum and kinetic energy are conserved. The total system kinetic energy before the collision equals the total system kinetic energy after the collision. If total kinetic energy is not conserved, then the collision is referred to as an inelastic collision.

In the collision between the two cars, total system momentum is conserved. Yet this might not be apparent without an understanding of the vector nature of momentum. Momentum, like all vector quantities, has both a magnitude (size) and a direction. When considering the total momentum of the system before the collision, the individual momentum of the two cars must be added as vectors. That is, 20 000 kg*m/s, East must be added to 10 000 kg*m/s, North. The sum of these two vectors is not 30 000 kg*m/s; this would only be the case if the two momentum vectors had the same direction. Instead, the sum of 20 000 kg*m/s, East and 10 000 kg*m/s, North is 22 361 kg*m/s at an angle of 26.6 North of East. Since the two momentum vectors are at right angles, their sum can be found using the Pythagorean theorem; the direction can be found using SOH CAH TOA (specifically, the tangent function). The value 22 361 kg*m/s is the total momentum of the system before the collision; and since momentum is conserved, it is also the total momentum of the system after the collision. Since the cars have equal mass, the total system momentum is shared equally by each individual car. In order to determine the momentum of either individual car, this total system momentum must be divided by two (approx. 11 200 kg*m/s). Once the momentum of the individual cars are known, the after-collision velocity is determined by simply dividing momentum by mass (v=p/m).

An analysis of the kinetic energy of the two objects reveals that the total system kinetic energy before the collision is 250 000 Joules (200 000 J for the eastbound car plus 50 000 J for the northbound car). After the collision, the total system kinetic energy is 125 000 Joules (62 500 J for each car). The total kinetic energy before the collision is not equal to the total kinetic energy after the collision. A large portion of the kinetic energy is converted to other forms of energy such as sound energy and thermal energy. A collision in which total system kinetic energy is not conserved is known as an inelastic collision.

REFERENCES:

Kai,L.H.(2010).The Physics of Car Collisions. Retrieved December 16, 2014 from http://3o318- physics-carcollisions.blogspot.com/

Townsend,B.(2002). The Physics of Car Collisions. Retrieved December 16, 2014 fromhttp://ffden2.phys.uaf.edu/211_fall2002.web.dir/ben_townsend/PhysicsofCarCollisions.htm

Borges,D.(2014). The Physics of Car Collisions. Retrieved December 16, 2014 from http://outreach.phas.ubc.ca/phys420/p420_96/danny/danweb.htm