Question

If the atmospheric pressure in a housing area is ${10}^5$Pa. What is the magnitude of the force exerted by the atmospheric gas on a flat horizontal roof of dimensions $5m\times 4m$?

• A. $2\times {10}^7$ N
• B. $2\times {10}^6$ N
• C. $4\times {10}^6$ N
• D. $8\times {10}^6$ N

Answer 1

The correct option is B $2\times {10}^6$ N

Area of the roof = $length\times breadth$ = $5m\times 4m$ = 20 $m^2$
Now, we know Pressure = $\frac{\text{Force}}{Area}$
So, Force F = $Pressure\times Area$
F = ${10}^{5}Pa\times 20m^2$ = $2\times {10}^6$ N