Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

When we push something it moves due to the disturbance in it's molecular arrangement causing waves. How do I calculate the speed of push/waves? http://www.youtube.com/watch?v=Dnv-Pm4ehFs The push actually depends on the amount of the force applied, right? That is, the push is force dependent, so how does he state the magnitude of it?

share|improve this question
2  
Look up "speed of sound". –  Olin Lathrop Jun 26 '13 at 13:38
1  
the speed of "push" or a longitudinal wave depends upon the medium's properties such as tension, density etc. and not on the force applied. –  udiboy1209 Jun 26 '13 at 14:20
    
then how come in the video he precisely stated the magnitude of the push –  gkshindia Jun 26 '13 at 14:28
    
Also a tansverse effect travels with longitudinal one. Like a polaron moving. If you push faster than the actual push speed(relative to bulk), it breaks right? –  huseyin tugrul buyukisik Jun 27 '13 at 12:15

1 Answer 1

To get an idea calculate the solid wave speed $c = \sqrt{\frac{E}{\rho}}$ where $E$ is the modulus of elasticity and $\rho$ is the density.

The actual wave speed is different, but this when get you close enough for what you want.

Example

Steel with $E=2\cdot 10^{11} \; {\rm N/m^2}$ and $\rho = 7680 \;{\rm kg/m^3}$ has wave speed

$$ c = \sqrt{\frac{2\cdot 10^{11}}{7680}} = 5103\; {\rm m/s} $$

share|improve this answer

protected by Qmechanic Aug 21 at 12:03

Thank you for your interest in this question. Because it has attracted low-quality answers, posting an answer now requires 10 reputation on this site.

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.