HW #6-3-solutions

# HW #6-3-solutions - pasha(sep635 HW 6-3 Antoniewicz(56445...

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pasha (sep635) – HW 6-3 – Antoniewicz – (56445) 1 This print-out should have 14 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 (part 1 of 2) 4.0 points AmassoF0 . 22 kg hangs From a vertical spring in the lab room. You grab hold oF the mass and throw it vertically downward. The speed oF the mass just aFter leaving your hand is 3 . 38 m / s . While the mass moved downward a distance oF 0 . 07 m, how much work was done on the mass by the Earth? Use g =9 . 8m / s 2 . Correct answer: 0 . 15092 J. Explanation: We can write W Earth = ~ F · Δ ~ r = h 0 , - mg, 0 i · h 0 , Δ y, 0 i =(0 . 22 kg)(9 . / s 2 )(3 . 38 m / s) = 0 . 15092 J . 002 (part 2 of 2) 4.0 points The speed oF the mass has decreased to 2 . 83 m / s. How much work was done on the mass by the spring? Correct answer: - 0 . 526625 J. Explanation: Δ KE = W spring + W Earth W spring = Δ - W Earth = 1 2 m ± ± ~ v f ± ± 2 - 1 2 m | ~ v i | 2 - W Earth = - 0 . 526625 J . 003 (part 1 of 6) 2.0 points Alithiumnucleushasmass5 . 1 × 10 - 27 kg. IF its speed is 0 . 986 c (that is, v/c =0 . 986), what is the particle energy? Use c =3 × 10 8 m / s. Correct answer: 2 . 7527 × 10 - 9 J. Explanation: The particle energy is just the total energy, given by E = γ mc 2 . So we have E = 1 s 1 - ² v c ³ 2 2 = 1 p 1 - 0 . 986 2 (5 . 1 × 10 - 27 kg) c 2 = 2 . 7527 × 10 - 9 J . 004 (part 2 of 6) 2.0 points What is the rest energy? Correct answer: 4 . 59 × 10 - 10 J. Explanation: The rest energy is just E rest = 2 =(5 . 1 × 10 - 27 kg) c 2 = 4 . 59 × 10 - 10 J . 005 (part 3 of 6) 2.0 points What is the kinetic energy? Correct answer: 2 . 2937 × 10 - 9 J. Explanation: The kinetic energy is given by = E - E rest =2 . 7527 × 10 - 9 J - 4 . 59 × 10 - 10 J = 2 . 2937 × 10 - 9 J . 006 (part 4 of 6) 2.0 points Next, an electric Force acts on the lithium nucleus and does 4 . 7 × 10 - 9 Jontheparticle. Now what is the particle energy?

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HW #6-3-solutions - pasha(sep635 HW 6-3 Antoniewicz(56445...

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