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Unformatted text preview: louey (cal2859) – Ch4-HW4 – florin – (56930) 1 This print-out should have 24 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 (part 1 of 2) 10.0 points If an object is moving with constant momen- tum vectorp = ( 12 , − 12 , − 10 ) kg · m / s , what is the magnitude of the rate of change of momentum dvectorp dt ? Correct answer: 0 kg · m / s. Explanation: A constant momentum implies that the rate of change of momentum is zero. 002 (part 2 of 2) 10.0 points What is the magnitude of the net force acting on the object? Correct answer: 0 N. Explanation: By the Momentum Principle, Δ vectorp = vector F net Δ t, if the rate of change of momentum is zero, then the net force is also zero. 003 (part 1 of 4) 10.0 points A ball whose mass is 1 . 3 kg is suspended from a spring whose stiffness is 3 N / m. The ball oscillates up and down with an amplitude of 14 cm. Take g = 9 . 8 m / s 2 . What is the angular frequency ω ? Correct answer: 1 . 51911 rad / s. Explanation: The angular frequency is given by ω = radicalbigg k m = radicalBigg 3 N / m 1 . 3 kg = 1 . 51911 rad / s . 004 (part 2 of 4) 10.0 points What is the frequency? Correct answer: 0 . 241774 s- 1 . Explanation: The frequency is given by f = ω 2 π = . 241774 s- 1 . 005 (part 3 of 4) 10.0 points What is the period? Correct answer: 4 . 1361 s. Explanation: The period is given by T = 1 f = 1 . 241774 s- 1 = 4 . 1361 s . 006 (part 4 of 4) 10.0 points Suppose this apparatus was taken to the Moon, where the strength of the gravitational field is only 1/6 of that on Earth. What would the period be on the Moon? (Consider care- fully how the period depends on properties of the system; look at the equation.) Correct answer: 4 . 1361 s. Explanation: This period is the same as the period you found in part 3, since g does not enter the formula for T ....
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This note was uploaded on 03/20/2012 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.
- Spring '08