The Earth itself is a source of terrestrial radiation. Radioactive materials including uranium, thorium, and radium exist naturally in soil and rock. Essentially all air contains radon<span> , which is responsible for most of the dose that Americans receive each year from natural background sources.</span>
It’s the engery. you are changing the engery
I found this using the app Socratic. When I took physics in high school it helped me so much.
The answer is c 1386j
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The work done is 375 J
Explanation:
The work done by a force in moving an object is given by

where
F is the magnitude of the force
d is the displacement
is the angle between the direction of the force and the displacement
In this problem,
F = 75 N is the force applied to the couch
d = 5 m is the displacement
Assuming the force applied to the couch is parallel to the motion, 
And so, the work done is

Learn more about work:
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