A10 kg box initially at rest is pulled with a 50 n horizontal force for 4 m across a level surface. the force of friction acting on the box is a constant 20 n. how much work is done by the gravitational force?
a. 10 j
b. 0 j
c. 50 j
d. 100 j

when atmosphere interacts with biosphere they focuses on on the sources and sinks of green house gases (ghgs) air pollutants, particular matters, water and energy between the earth's surface and the atmosphere. the biosphere affects the climate. the atmosphere and biosphere are in constant interaction with each other, and all living things rely on gases in the atmosphere for life. organisms such as animals take in oxygen gas form the atmosphere to use in every cell of their body for smooth functioning of daily routine exercises.

the answer would be a

i think is conclusions.i think so