A scientist uses a variable frequency microphone/speaker system (sonar) to measure the depth of water. In freshwater (were sound travels at 1490 m/s) and 120 Hz sound is sent from a stationary ship to the bottom of a deep lake and the time interval between the generation and detection of the echo takes 1.14 seconds. What is the distance from the ship to the bottom of the lake?

hello there!

your answer is a “generator”

a generator does not create energy but instead it transforms it.

it’s basically a motor working in reverse.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =