A truck travels at a constant speed of 45 m/s. How much work did the truck engine do during a 2 hour period if it supplied a force of 25 kN of force.

Answer is in the photo. I can't attach it here, but I uploaded it to a file hosting. link below! Good Luck!

tinyurl.com/wpazsebu

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.

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 =