A 65kg person climbs up a set of stairs to a height of 9m in 30 seconds, what is the force that he must exert to get up the stairs ?

The force exerted must be 0.65N

Explanation:

Given:

Mass, m = 65 kg

Height, h = 9m

Time, t = 30 seconds

Force, F = ?

We know:

distance = speed X time

9 = s X 30

s = 0.3 m/s

Acceleration, a =

Force = mass X acceleration

Force = 65 X 0.01 N

F = 0.65N

Therefore, the force exerted must be 0.65N

the closer the planet is to the sun, the larger the gravity

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 =