# Homework Help: Wavelength speed tension

1. Jul 9, 2008

### 0338jw

1. The problem statement, all variables and given/known data

a ski gondola is connected to the top of a hill by a steel cable of length 620m and diameter 1.5cm (r=.015m) As the gondola comes to the end of its run it bumps into the terminal and sends a wave pulse along the cable. It is observed that it took 16 s for the pulse to return a. what is the speed of the pulse? what is the tension in the cable?

2. Relevant equations
v=$$\lambda$$*f
v=$$\sqrt{F/(m/L)}$$
f=1/T

3. The attempt at a solution
how would I relate the length and diameter to mass of the cable? I think I'm missing an equation, but all the others seem to be for springs or pendulums. If the period is 16 seconds, then I would have frequency as .063Hz and I could just use twice the length of the cable, for a full wave? Am I headed in the correct direction?

2. Jul 9, 2008

### alphysicist

Hi 0338jw,

They say the cable is made of steel; what property of steel could you look up that relates mass and the dimensions of the cable?

The pulse took 16 seconds to travel from the end, to the beginning, and back to the end. How far did it go in those 16 seconds? Then what would the speed be?

3. Jul 9, 2008

### 0338jw

so when I find mass per unit length using mass per unit length and density I get 1.39 kg/m. I solved for frequency and I got .063 Hz. When I used wave equation for speed with 2* 620m because it had to go back and forth I get 78.12m/s. Is this correct? I'm going on to find the tension using this value