exam1_spring2009

# exam1_spring2009 - Physics 251 exam 1 March 4 2009 You may...

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Unformatted text preview: Physics 251 exam 1, March 4, 2009. You may use a calculator, and the equation sheet that I have provided. 1. Blubbo, a rather rotund, 2-meter-diameter superhero, has an amazing ability to heal as long as a spear is fully contained within him for a moment in time from his perspective, rather than sticking out of him front and back. Bruto throws a spear (it measures 3 meter long in its own inertial frame) at Blubbo. How fast does the spear need to traveling for Blubbo to survive the attack? Answer: From Blubbo’s perspective, the spear needs to be relativistically contracted from 3 meters to 2 meters, or (2 meters)=(3 meters)/ γ or γ = 3 / 2 , giving β = radicalBig 1- 1 /γ 2 = radicalBig 1- 4 / 9 = radicalBig 5 / 9 = 0 . 745 or v = 0 . 745 c = 2 . 24 × 10 8 m/sec. 2. While rushing to arrive nice and early for your 8:20 am recitation section so that you make your professor exceedingly happy, you get pulled over by a police officer for running a red ( λ = 600 nm) light. You tell the police officer that it looked green ( λ = 500 nm) to you. The police officer responds by adding a speeding ticket to your list of offences. What speed does the police officer write down on the ticket?...
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exam1_spring2009 - Physics 251 exam 1 March 4 2009 You may...

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