Which the following statements about the force of friction is true?

a. friction acts in the direction opposite to weight.

b. friction acts in the same direction as the normal force.

c. friction acts in the same direction as weight.

d. friction acts in the direction opposite to an object's motion.

who knows how to do this?

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it

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 =

490 n

f=125n a=2.5m/s2