- #1
smashd
- 10
- 1
Homework Statement
A geologist is at the bottom of a mine shaft next to a box suspended by a vertical rope. The geologist sends a signal to his colleague at the top by initiating a wave pulse at the bottom of the rope that travels to the top of the rope. The mass of the box is 20.0 kg and the length of the rope is 80.0 m. If a wave pulse initiated by the geologist takes 1.26 s to travel up the rope to his colleague at the top, find the mass of the rope.
[/B]
d = 80.0 m
t = 1.26 s
mrope = ?
The answer is mrope = 4.30 kg.
Homework Equations
## v = \sqrt{{\frac{Tension}{μ}}} ##[/B]
The Attempt at a Solution
I know the answer but I can't come up with it myself.
At first I thought I could use kinematics to find the initial velocity of the wave speed at the bottom of the rope, but I realized that wave speed is determined by the medium and not only by a constant acceleration. E.g.:
## v = \sqrt{{\frac{Tension}{μ}}} = \sqrt{{\frac{m_{samples} g}{{\frac{m_{rope}}{d}}}}} ≠ {\frac{d - {\frac{1}{2}} g t^2}{t}} ##
So I guess what I have trouble with the most is figuring out where or how I use the t = 1.26 s information.
How do I connect these pieces?