Chapter 13.1, Problem 1PP

To determine

To Calculate:The force at sea level that air exerts on the top of a desk.

Answer to Problem 1PP

  $1.2 \times {10}^5\text{ N}$

Explanation of Solution

Given data:

The atmospheric pressure at sea level is about $1.0\times {10}^5 \text{Pa}$ .

Length of the desk, $l=152\text{cm = 1}\text{.52 m}$

Width of the desk, $w=76\text{cm = 0}\text{.76 m}$

Formula used:

A force (per unit area) that acts on any object is defined by pressure. Pressure on any object is calculated by using formula

  $P=\frac{F}{A}$

Where,F = force and A = Area

Area of the desk can be obtained by: $A=l\times w$

Calculation:

By using the formula of a pressure, calculate the force

  $F=PA$

Now, substitute the given values in above equation,

  $\begin{array}{c}F=\left(\text{1}\text{.0}{\text{×10}}^{\text{5}}\text{Pa}\right)\left(\text{1}\text{.52 m}\times 0.76\text{m}\right)\\ \approx \text{1}{\text{.2×10}}^{\text{5}}\text{N}\end{array}$

Conclusion:

The answer is $1.2 \times {10}^5\text{ N}$ .