3. We’ve talked mostly about work and potential energy in this lab because kinet

Question

3. We’ve talked mostly about work and potential energy in this lab because kinetic energy is difficult to explore with the equipment we have; nonetheless, it’s just like any other energy and is easy to deal with. In lab we had the work due to friction removing potential energy from a system. Friction can also bleed off kinetic energy. Police use this fact in traffic investigations. Imagine an aspiring young lab coordinator at age 17 getting a rusty ’66 pickup ready for a Styx concert when another teenager comes speeding around a corner who dings his sweet ride halfway down the block. The offending vehicle locked its brakes and left an 88 ft long skid mark (as measured by police) on the dry asphalt. As the responding officer on the scene, use the following information from your physics folder (cops actually have these) to determine whether or not to add a ticket for speeding in a 30 mph zone in addition to reckless driving. Cite evidence. Coefficient of Friction between commercial tires and various road surfaces and conditions Dry Wet Concrete 0.68 0.58 Asphalt 0.67 0.53 Hints: If a variable or quantity is not given, you probably do not need it. The road is level so the potential energy before and after the skid is zero. Consider all boxed and labeled equations from this lab. Use the internet, built in calculator functions, or hand conversions to switch between metric and English units when necessary. Further hints: energy conservation. PEbefore + KEbefore – Wremoved by friction = PEafter + KEafter

Explanation / Answer

it has stopped after travelling 88 f or 26.822 m

coefficient of friction is 0.53

we know that

d = V^2/2ug

V = sqrt ( 2ugd)

V = 16.6 m/s = 37mph

so teenager shoul be fined

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