An object falls freely in a straight line and experiences air resistance proportional to its speed; this means its acceleration is a(t)equals minuskv(t), where k is a positive constant and v is the object's velocity. the speed of the object decreases from 1100 ft divided by s to 1000 ft divided by s over a distance of 1300 ft . approximate the time required for this deceleration to occur. hint: note that a(t)equals v prime (t ) and v(t)equals x prime (t ).
the time required for this deceleration to occur is approximately seconds. (do not round until the final answer. then round to four decimal places as needed.)

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.

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 =

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y