Speed of waves

[staceyrho]

I'm working on a physics problem and I think I'm on the right path but not sure? I also think I need to convert but not sure to what. Here is my question:

A String is stretched and fixed at both ends, 273 cm apart. If the density of the string is 0.0093 g/cm and it's tension is 1310 N, what is the speed of the traveling waves? Answer in units of m/s.

Here is the formula i've been trying to work with but I'm stuck on the N, and cm in this problem, so i'm not sure if this is correct.

V=square root T/P (I don't know how to type the square root sign)

square root 1310N/273 cm the answer i'm gettin is 0.0126127 but do I convert my N and cm before dividing or is this totally wrong?

 

[skeeter]

the formula is v = sqrt[(tension)/(linear density)]

why are you using the 273 cm string length to calculate v? use the given linear density, but do the conversion before calculating the square root ...

(.0093 g/cm)(1 kg/1000 g)(100 cm/m) = .00093 kg/m

v = sqrt[(1310 N)/(.00093 kg/m)]

now calculate v.

 

[staceyrho]

Okay I'm having trouble with the conversion. I get 8.42569 when I divide the 1310n by .00093kg, but I'm lost at this point with the conversion. 1 kg= 9.8 N according to my book, but I am not sure what my answer is N or kg?

 

[skeeter]

I did the the necessary conversion for you. Why are you trying to convert kg into N?

the formula takes the square root of a force divided by a linear density ... do the dimensional analysis

sqrt[N/(kg/m)] = sqrt[(kg*m/s²)/(kg/m)] = sqrt(m²/s²) = m/s

all you have to do is calculate v = sqrt[1310/.00093] = 1.2 x 10³ m/s

 

[staceyrho]

your answer is incorrect as well. I'm not sure what you did to get 1.2x10 (3). Can you explain I enter my answers on a website that tells me if they are incorrect and this one is wrong, so now i'm really confused