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 0.00350 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)

N = 177843 sheets

Explanation:

We are given;

Mass; m = 0.0035 kg

Pressure; p = 101325 pa = 101325 N/m²

L = 0.279m

W = 0.216m

The weight of N sheets is N (mg)

Where;

m is the mass of one sheet

N is number of sheets

g is the acceleration due to gravity.

The pressure equals weight divided by the area on which the weight presses:

Thus,

p = F/A = Nmg / (L•W)

Therefore, making N the subject;

N = pLW / (mg)

N = 101325 x 0.279 x 0.216 / (0.0035 x 9.81)

N = 177843