Humans evolved in Earth's atmosphere, therefore the pressures interior to the body are relatively close to atmospheric pressure. Because the differences between internal body pressures and atmospheric pressure are so small, individuals have a difficult time gauging the magnitude of atmospheric pressure. Suppose an individual is lying on his stomach with sheets of paper stacked on his back. If each sheet of paper has a mass of 0.00290 kg and is the standard letter size of 8.5 in by 11 in ( 0.216 m by 0.279 m ), how many sheets must be stacked to produce a pressure on his back equal to atmospheric pressure (roughly 101325 Pa )

The answer is 214857.49 sheets

Explanation:

The force by n sheets is:

F = n*m*g = n*0.00290*9.8 = 0.02842n

The pressure is:

P = F/A

The area A is:

A = 0.216 * 0.279 = 0.060264 m²

Clearing n from equation of pressure:

v=ir = 3x15 =45 v

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.