A roller-coaster car has a potential energy of 700 kJ and a kinetic energy of 160 kJ at point A in its travel. At the low point of the ride,
the potential energy is zero, and 60 kJ of work has been done against friction since it left point A. What is the kinetic energy of the
roller coaster at this low point?

probably not if net force is zero

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 =

the answer is false. this is because for ice to melt, it requires latent heat of melting. latent heat means heat energy required to change phase without any increase in temperatures. therefore, the ice will take energy from the environment to melt hence atmospheric temperatures will reduce.