# Physics Project 2 Younghun Brian Wi, Sam Magliaro Section 001.

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Physics Project 2 Younghun Brian Wi, Sam Magliaro Section 001

Opening scene of Constantine (2005) where the guy gets hit by the car. Watch this http://www.youtube.com/watch?v= tYhZpXCMk-0

An inelastic collision is where an object impacts another object and they remain stuck together. Their mass becomes combined, but their momentum stays the same. Though the new combined object slows down, its mass increases, so the momentum is unchanged.

Using the inelastic momentum equation, we can figure out how much the man should weigh to make the car stop dead in its tracks like it does in the film. Weight of Car: Car estimated to be a 1980 Lincoln Town Car = 1800kg

Speed of Car: Video file of movie is 24 frames/second 5 frames from when car enters frame until impact 5 frames / 24fps = 0.208s Actor estimated to be 1.8 meters tall (6 feet) Approximately 4 feet of man showing in frame; used as ruler to measure distance to edge of frame where car enters (8 feet = 2.44m) 2.44m/0.208s = 11.73m/s = about 26mph

Conservation of Momentum (Inelastic collision): m1v1 + m2v2 = mfvf 1800kg(11.73m/s) + m2(0m/s) = mf(0m/s) 21,114 + 0 = 0 = impossible! It is physically impossible for the car to hit someone and have both instantly become immobile. The mass of the person would have to be infinite.

Alter final speed to be close to 0. Vf = 0.0001m/s. This should give us an actual result. 1800kg(11.73m/s) + m2(0m/s) = mf(.0001m/s) Remember that it’s an inelastic collision. mf = m1 + m2 21,114 + 0 = (1800 + m2)(.0001) 21,114/.0001 = 1800 + m2 211,114,000 = 1800 + m2 211,112,200 kg = m2

The man would have to be 211,112,200 kg to stop the car like that. That’s 465,422,732 pounds, which is over 232,000 tons! That’s the weight of 310 U.S. aircraft carriers The Empire State Building weights 360,000 tons.

Let’s estimate that the man actually weighs 180 pounds (81.6kg). 1800(11.73) + 81.6(0) = 1881.6(vf) 21,114 = 1881.6(vf) vf = 11.22m/s = 25.1mph The actual speed of the car would be changed very little.

Newton's 3 rd Law When an object applies force on another object, the second object exerts the same(opposite) force on the first object. Every action has an opposing same reaction.

Conclusion In the video, the car and the guy should’ve remain stuck together and moving at 25mph. In order to stop the car like in the video, he has to weigh so much. The purpose of this project was to prove with the knowledge we learned from the class that it cannot happen in real life.

Work cited David; (1960-2007). Fundamentals of Physics. John Wiley & Sons. Chapter 9. Serway, Raymond; Jewett, John (2003). Physics for Scientists and Engineers (6 ed.). Brooks Cole. Stenger, Victor J. (2000). Timeless Reality: Symmetry, Simplicity, and Multiple Universes. Prometheus Books. Chpt. 12 in particular. Tipler, Paul (1998). Physics for Scientists and Engineers: Vol. 1: Mechanics, Oscillations and Waves, Thermodynamics (4th ed.). W. H. Freeman. Hand, Louis N.; Finch, Janet D.. Analytical Mechanics. Cambridge University Press. Chapter 4.

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