Use the table to answer the question.
1750 to 2012
source
coal
oil
gas
cement production
land-use
carbon released (ppm)
86
64
26
76
sink
carbon absorbed (ppm)
land
68
76
ocean
if the atmospheric carbon concentration was 280 parts per million in 1750, what was the concentration in 2012?

Digestion because it removes waste

It depends on the surface of the levels. the rougher the surface, the greater is the frictional force. for rougher surfaces, you would need to exert greater force to move the object. the concept is that, you must overcome the frictional force in order to bring the object into motion. this is the reason why we add lubricants to the joints so they could easily move. this answer was on