Which of the following choices has the type of wave matched with a correct characteristic of that wave electromagnetic waves are always longitudinal mechanical waves are always a transverse electromagnetic waves always require a medium to travel mechanical waves always require a medium to travel

D.Mechanical waves always require a medium to travel.

Explanation:

Longitudinal waves: It is that type of waves in which waves  require a medium to travel.Longitudinal waves can be modeled by spring. Example: mechanical waves.

Transverse waves:It is that type of waves which may or may not require medium to travel depending upon the type of wave.Example:EM and ocean waves.

A.It is false because EM waves are always transverse waves.

B.It is false because mechanical waves are always longitudinal waves.

C.It is false because EM waves  always do not    require  a medium to travel.

D.It is true because mechanical waves are longitudinal waves which require a medium to travel.

D.Mechanical waves always require a medium to travel.

grav force prop 1/r squared 2r all squared is 4rsquared 1/4rsquared quartered

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 =