Calmweek12W13solutions

- HOMEWORK Week 12 Chapter 13 SOLUTIONS(13.2 A person in a rocking chair completes 12 cycles in 21 s What are the period and frequency of the

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HOMEWORK: Week 12 – Chapter 13 - SOLUTIONS (13.2) A person in a rocking chair completes 12 cycles in 21 s. What are the period and frequency of the rocking? SOLUTION 12 cycles 0.57 Hz 21 s 11 = 1.8 s 0.571 s f T f == (13.11) An atom in a molecule oscillates about its equilibrium position with a frequency of 200 10 14 . × Hz and a maximum displacement of 3.50 nm. (a) Write an expression giving x as a function of time for this atom, assuming that x A = at t = 0. (b) If, instead, we assume that x = 0 at t = 0, would our expression for position versus time use a sine function or a cosine function? Explain. SOLUTION (a) 14 14 1 14 1 2.00 10 Hz, 3.50 nm, and cos . 24 . 0 0 1 0 s (3.50 nm)cos[(4.00 10 s ) ] f Ax A t f xt ω ωπ π = = × (b) At t = 0, sin 0 t = (13.14) A mass attached to a spring oscillates with a period of 3.15 s. (a) If the mass starts from rest at x = 00440 . m and time t = 0, where is it at time t = 637 .? s (b) Is the mass moving in the positive or negative x direction at t = s Explain. SOLUTION (a) 2 (0.0440 m)cos . At 6.37 s, 3.15 s 2 (6.37 s) (0.0440 m)cos 0.0436 m 3.15 s t x ⎛⎞ ⎜⎟ ⎝⎠ (b) negative direction . x At t = 6.30 s (= 2 T ) the mass was at its largest displacement in the positive x direction. 0.07 s later it is headed toward the origin.
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(13.22) A peg on a turntable moves with a constant linear speed of 0.67 m/s in a
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This note was uploaded on 07/02/2011 for the course PHYS 201 taught by Professor Woodahl during the Fall '09 term at Indiana.

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- HOMEWORK Week 12 Chapter 13 SOLUTIONS(13.2 A person in a rocking chair completes 12 cycles in 21 s What are the period and frequency of the

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