A speed skater is sliding across the ice at a speed of 19 m/s when she encounters a rough patch of ice that is 2.0 m wide. As she coasts out of the rough patch, she is moving with a speed of 18 m/s. Assuming her deceleration to be constant, roughly what is the magnitude of that deceleration?

Explanation:

The motion of the skater is a uniformly accelerated motion, so we can find the deceleration by using the following suvat equation:

where

v is the final velocity

u is the initial velocity

a is the acceleration

s is the displacement

In this problem, we have:

u = 19 m/s is the initial velocity of the skater

v = 18 m/s is the final velocity of the skater

s = 2.0 m is the displacement

Solving for a, we can find the acceleration:

And the negative sign tells us that the acceleration is in the opposite direction to the motion (so, it is a deceleration)

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 =