An anchored fishing boat uses sonar to work out how deep would the water be if the echo took 2 seconds to return?

a) how deep is the water
b) if the boat was on a lake instead of the sea, how deep would the water be if the echo took 2 seconds to return.

c) why is it important that the sonar machine has the information about what kind of water the boat is in.

d) a little while later, the ultrasound machine detects two echoes from a ping, after 0.05 seconds and 0.7 seconds. suggest what these echoes mean..

i need the right answers for today