# Halliday

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Chapter 15

9. um auto-falante produz um som musical através das oscilações de um diafragma, cuja amplitude é limitada por.
The magnitude of the maximum acceleration is given by am = 2xm, where is the angular frequency and xm is the amplitude.

(a) The angular frequency for which the maximum acceleration is g is given by , and the corresponding frequency is given by

(b) Forfrequencies greater than 498 Hz, the acceleration exceeds g for some part of the motion.

10. qual é a constante de fase do oscilador cuja função. (do gráfico)
We note (from the graph) that xm =6.00 cm. Also the value at t = 0 is xo =  2.00 cm. Then Eq. 15-3 leads to

The other “root” (+4.37 rad) can be rejected on the grounds that itwould lead to a positive slope at t = 0.

11.a função x=(6m)cos[(3pi rad/s)t + pi/3 rad) descreve o movimento harmônico simples de um corpo.
(a) Making sure our calculator is in radians mode, wefind

(b) Differentiating with respect to time and evaluating at t = 2.0 s, we find

(c) Differentiating again, we obtain

(d) In the second paragraph after Eq. 15-3, the textbookdefines the phase of the motion. In this case (with t = 2.0 s) the phase is 3(2.0) + /3  20 rad.

(e) Comparing with Eq. 15-3, we see that  = 3 rad/s. Therefore, f = /2 = 1.5 Hz.

(f) Theperiod is the reciprocal of the frequency: T = 1/f  0.67 s.

12. qual é a constante de fase do oscilador harmônico cuja função (gráfico)
We note (from the graph) that vm = xm = 5.00 cm/s. Alsothe value at t = 0 is vo = 4.00 cm/s. Then Eq. 15-6 leads to