18. Waves & Sound

(II) The wave on a string shown in Fig. 15–35 is moving to the right with a speed of 1.10 m/s.

(b) Estimate the vertical speed of point A on the string at the instant shown in Fig. 15–35.

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(II) Suppose at t= 0 , a wave shape is represented by D = A sin (2π x/ λ + ϕ) ; that is, it differs from Eq. 15–9 by a constant phase factor ϕ. What will be the equation for such a wave as a function of x and t if it travels to the left along the x axis?

When you walk with a cup of coffee (diameter 8 cm) at just the right pace of about one step per second, the coffee sloshes higher and higher in your cup until eventually it starts to spill over the top, Fig 15–41. Estimate the speed of the waves in the coffee.

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