P18_070 - = R − 1 v R 1 cos θ = 0 90 m s where v = 1540 m/s θ = 20 ◦ and R = 1 5495 5 × 10 6(c We interpret the question as asking how ∆

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
70. (a) The blood is moving towards the right (towards the detector), because the Doppler shift in frequency is an increase :∆ f> 0. (b) The reception of the ultrasound by the blood and the subsequent remitting of the signal by the blood back toward the detector is a two step process which may be compactly written as f +∆ f = f µ v + v x v v x where v x = v blood cos θ. If we write the ratio of frequencies as R =( f +∆ f ) /f , then the solution of the above equation for the speed of the blood is v blood
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: = ( R − 1) v ( R + 1) cos θ = 0 . 90 m / s where v = 1540 m/s, θ = 20 ◦ , and R = 1 + 5495 / 5 × 10 6 . (c) We interpret the question as asking how ∆ f (still taken to be positive, since the detector is in the “forward” direction) changes as the detection angle θ changes. Since larger θ means smaller horizontal component of velocity v x then we expect ∆ f to decrease towards zero as θ is increased towards 90 ◦ ....
View Full Document

This note was uploaded on 11/12/2011 for the course PHYS 2001 taught by Professor Sprunger during the Fall '08 term at LSU.

Ask a homework question - tutors are online