Question

What is the ratio of the intensities of an earthquake PP wave passing through the Earth and detected at two points 19 kmkm and 46 kmkm from the source?

Answer 1

Answer:

The ratio of the intensities is roughly 6:1.  

Step-by-step explanation:

The intensity I() of an earthquake wave is given by:

$I = \frac{P}{4\pi d^{2}}$

where P: is the power ans d: is the distance.

Hence, the ratio of the intensities of an earthquake wave passing through the Earth and detected at two points 19 km and 46 km from the source is:

$\frac{I_{1}}{I_{2}} = \frac{P/4\pi d_{1}^{2}}{P/4\pi d_{2}^{2}}$

where I₁ = P/4πd₁², d₁=19 km, I₁ = P/4πd₂² and d₂=46 km    

$\frac{I_{1}}{I_{2}} = \frac{d_{2}^{2}}{d_{1}^{2}}$

$\frac{I_{1}}{I_{2}} = \frac{46 km^{2}}{19 km^{2}}$

$\frac{I_{1}}{I_{2}} = 5.9:1$

Therefore, the ratio of the intensities is roughly 6:1.  

 

I hope it helps you!