A traveling wave on an infinite string, find the intensity

AI Thread Summary
The discussion revolves around calculating the intensity of a traveling wave on an infinite string, with the initial answer mistakenly given as 40 Watts. Participants point out errors in the equations used, particularly the confusion between units of power and frequency, noting that Hz is not a unit of power. The importance of showing the working steps to identify mistakes is emphasized, as well as the correct relationship between wave speed, tension, and density. Clarification is sought on how the wavelength was determined, indicating that more information is needed to diagnose the problem accurately. The conversation highlights the need for precise calculations and unit consistency in wave mechanics.
LCSphysicist
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Homework Statement
I will post below.
Relevant Equations
.
1598913360062.png

The answer is about 40 Watts, but i am really not getting it:
<Pot> = 0.5((pλ)(ωA)²)v

p density linar
λ wavelength
ω angular frequency
A amplitude
v phase speed

Why is this wrong?

(I already tried too by <Pot> = Z*(ωA)²/2)

Z is impedance
 

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LCSphysicist said:
The answer is about 40 Hz
Hz is not a unit of power. Did you mean Watts?
 
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berkeman said:
Hz is not a unit of power. Did you mean Watts?
Opsss, yes >.< i wrote wrong
 
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The Relevant Equations: has an error.
It shows '1 lb = 3[/color][/color]54 gm-wt', it should be 4[/color]54 gm-wt.[/color][/color][/color][/color]
 
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LCSphysicist said:
i am really not getting it:
Where is your working? How did you find the wavelength?
We cannot say what is wrong without seeing what you did.
 
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haruspex said:
Where is your working? How did you find the wavelength?
We cannot say what is wrong without seeing what you did.
v = √T/ρ = λ*f is what i am using to find the speed
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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