An electron of mass 9.11×10−31 kg leaves one end of a tv picture tube with zero initial speed and travels in a straight line to the accelerating grid, which is a distance 2.20 cm away. it reaches the grid with a speed of 2.70×106 m/s . the accelerating force is constant.

Explanation:

We have given that mass of electron

It is given that initial velocity u=0 m/sec

Final velocity v =

Distance S = 2.2 cm = 0.022 m

According to third law of motion

Accelerating force F is given by F = ma

So accelerating force

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 =

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.