Joe follows the procedure below to make a compass.
1. move a magnet from the top of a needle to its point fifty times.
2. lay the needle on a cork that is floating in a bowl of water.
3. observe the direction that the needle points.
what is the purpose of step 1?

a. to give the needle an electric charge
b. to make the needle sharper
c. to magnetize the needle
d. to flatten the side of the needle

explanation: in any substance/object, the particles inside it (atoms/molecules) constantly move in random directions and with random speeds (this motion is called brownian motion). as a result, the particles have some kinetic energy (which is proportional to the temperature of the substance).

explanation:

have a great day!

the independent variable, or the one that is intentionally manipulated is the speed.

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 =