## Answers to Sound and Ultrasound Questions

1) wavespeed = frequency x wavelength = 200 x 20000 = 4000000m/s

b) time = distance/ speed = 20m (remember the sound has to go there and back) / 4000000 = 5 microseconds

c) It has a higher pitch

2) 10m

b) speed = distance/time = 10/3 = 3.3m/s

c) frequency = speed/wavelength = 3.3/0.3 =11Hz

3) time = distance/speed = 0.05 (remember to turn cm into m)/ 300 = 0.000017s

b) It has to go there and back so will take twice as long =0.000033s

c) wavelength = frequency/ wavespeed = 2000000 ( remember MHz are million Hz) / 300 = 6700m

b) time = distance/ speed = 20m (remember the sound has to go there and back) / 4000000 = 5 microseconds

c) It has a higher pitch

2) 10m

b) speed = distance/time = 10/3 = 3.3m/s

c) frequency = speed/wavelength = 3.3/0.3 =11Hz

3) time = distance/speed = 0.05 (remember to turn cm into m)/ 300 = 0.000017s

b) It has to go there and back so will take twice as long =0.000033s

c) wavelength = frequency/ wavespeed = 2000000 ( remember MHz are million Hz) / 300 = 6700m