Chapter 13.1, Problem 11SSC

(a)

To determine

To Compare: The pressure of the air on the outside of the two boxes.

Answer to Problem 11SSC

The pressure remains the same.

Explanation of Solution

Introduction:Force is an interaction between two or more than two objects, that causes a pull or push action between those objects. A force (per unit area) that acts on any object is defined by pressure. Pressure on any object is calculated by using formula

  $P=\frac{F}{A}orF=PA$

Where, P = Pressure, F = Force and A = Area

Dimension of first box is $\text{20 cm×20}\text{cm×}\text{20}\text{cm}\text{.}$ Dimension of second box is $\text{20 cm×20}\text{cm×}\text{40}\text{cm}\text{.}$ Both of these boxes are each suspended by thin strings in midair. As per definition, the pressure of the air will be same on the two boxes.

Conclusion:

The pressure will remain same.

(b)

To determine

To Compare: The magnitude of the total force of the air on the two boxes.

Answer to Problem 11SSC

Second box has twice the total force of the first box.

Explanation of Solution

Introduction:Force is an interaction between two or more than two objects, that causes a pull or push action between those objects. A force (per unit area) that acts on any object is defined by pressure. Pressure on any object is calculated by using formula

  $P=\frac{F}{A}orF=PA$

Where, P = Pressure, F = Force and A = Area

Dimension of first box is $\text{20 cm×20}\text{cm×}\text{20}\text{cm}\text{.}$ Dimension of second box is $\text{20 cm×20}\text{cm×}\text{40}\text{cm}\text{.}$ Both of these boxes are each suspended by thin strings in midair

Because $F=PA$ , total force of the air is greater on the box with the greater area. The second box has twice the surface area. Thus, it has twice the total force of the first box.

Conclusion:

The second box has double the net force as compared to the first box.