A string oscillates according to the equation(adsbygoogle = window.adsbygoogle || []).push({});

y´ = (0.654 cm) sin[(π/4.0 cm^{-1})x] cos[(24.2π s^{-1})t].

What are the (a) amplitude and (b) speed of the two waves (identical except for direction of travel) whose superposition gives this oscillation? (c) What is the distance between nodes?(d) What is the transverse speed of a particle of the string at the position x = 1.24 cm when t = 1.13 s?

Give your answers in centimeter-based units.

I only need help with part d, the other parts I have gotten right.

Here's my attempt at solving:

u = ∂y´/∂t = (0.654 cm) (24.2π s^{-1}) sin[(π/4.0 cm^{-1})x] (-1) sin[(24.2π s^{-1})t]

Then, plugging in x and t:

u = (-0.654 cm) (24.2π s^{-1}) sin[(π/4.0 cm^{-1})(1.24 cm)] sin[(24.2π s^{-1})(1.13 s)]

u = -32.9 cm/s

When I plug this solution in, I am told that it is not the correct answer. Even when I tried neglecting the negative sign. I am not sure how my calculations are wrong, but I would love to be enlightened!

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# Homework Help: Oscillating String - Transverse Speed, what am I doing wrong?

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