3. The density of skin is 1.15 g/cm 3 while the density of fat is 0.95 g/cm3. The velocity of ultrasound waves in skin is 1730 m/s while 1450 m/s in fat. Calculate the intensity reflection coefficient if ultrasound waves pass from skin to fat. How many percent of the waves is reflected? Intensity Reflection coefficient Intensity Reflection coefficient Skin (21 ) a = (2 2- 21 ) 2 Dimensional Analysis (22 + 21 ) 1 kg cm3 1000g 100 cm 13= 1150 Kg = ( 1 3 8 x 10 6 - 1 9 9 x 10 6 ) 2 Im 3 27 w of the ms Acoustic Impudence ( 1 3 8 X 10 + 19 9 x 10 4 ) 2 waves are reflected Z= Pr z= ( i150 Kg ) ( 1730 m) = 199x10" kg m 3 = 03247 DV 3 2710 Fat ( 23) Dimensional Analysis 095 9 1kg (1010m )5 950 Kg cm 3 6 10 019 Im Acoustic Impudence (950ng ) ( 1450 m ) = 2"= 138 x 10' ng mis