The the x and y vector velocity components of a moving object are given as vy = 6.5 m/s and vx = –3.1 m/s. Calculate the resultant velocity and direction.

In this kind of vector additions, we use Pythagorean theorem, which is √(Vx² + Vy²)

If we use it, the velocity is found to be √(-3.1² + 6.5²) ≅ 7.20 m/s

And when it comes to the direction, I want you to think of coordinate system and a compass. X coordinate is negative and Y coordinate is positive. The direction is northwest (not strictly).

If you think anything is wrong, or you have anything that you do not understand, please let me know. I am sorry for my bad English by the way ^^

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 =