The velocity of a car teduces from 30 km/h as the car approaches a stop sigh. is this an example of positive or negative accelerationthe

The stopping car has negative acceleration.

Explanation:

 We know acceleration is the rate of change of velocity. That is

            Acceleration(a) = ( Final velocity - Initial velocity )/ Time taken.

            Here Final velocity = 0 km/h( car stops) and initial velocity = 30 km/h

             So acceleration = (0-30)/time = -30/ time

             Time is always positive , so -30/time is negative, so the stopping car has negative acceleration.

hèllo, sorry i really need some more points so if you need this qustion answered than retype 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 =