Homework Help: Mass of a String

1. Jan 19, 2010

Samurai Weck

1. The problem statement, all variables and given/known data
A 1.50-m-long string is under 30.0 N of tension. A pulse travels the length of the string in 50.0 ms.

2. Relevant equations

v of string = sq rt of (Tension of string/ string's mass-to-length ratio)

string's mass to length ratio= m/L

3. The attempt at a solution

So, the pulse takes 50.0 ms to travel through 1.5 m of string. So, the velocity of the pulse is 1.5 m/.050 s.

V= 1.5/.050 = 30 m/s

Now that I know the velocity, I can use the V of string equation.

V$$^{2}$$= T/$$\mu$$
$$\mu$$= T/V$$^{2}$$
$$\mu$$= 30.0N/ (30m/s)$$^{2}$$
$$\mu$$=.033

$$\mu$$=m/L
$$\mu$$*L=m
.033*1.5=m
m=.049995 or .05 g

However, master physics disagrees with this answer. What am I doing incorrectly?

Last edited: Jan 19, 2010
2. Jan 19, 2010

kuruman

The answer should be in kilograms not grams.

3. Jan 19, 2010

Samurai Weck

Actually, the unit they want mass in is g. Sorry. Forgot to put that in there.

4. Jan 19, 2010

kuruman

I was not clear explaining what I meant. The answer that you got, 0.05 is in kilograms. You need to convert that to grams. Did you enter 0.05?