Chapter 1, Problem 1.19P

Interpretation Introduction

(a)

Interpretation:

The force in newtons exerted on the gas by the atmosphere, the piston and the weight should be determined assuming there is no friction between piston and cylinder.

Concept Introduction:

The force exerted on the gas by the atmosphere can be calculated as follows:

  $F=PA$

Here, P is pressure and A is area of cross-section

Also, force exerted by an object is as follows:

  $F=ma$

Here, m is mass of object and a is acceleration.

Interpretation Introduction

(b)

Interpretation:

The pressure of the gas should be calculated in kPa.

Concept Introduction:

The pressure of the gas can be calculated as follows:

  $P=\frac{F}{A}$

Here, F is force and A is area of cross-section.

Interpretation Introduction

(c)

Interpretation:

The work done by the gas in kJ and the potential energy change of the piston and weight should be determined.

Concept Introduction:

The work done by gas can be calculated as follows:

$\text{W = F}\Delta \text{L}$

Here, F is force and $\Delta \text{L}$ is displacement.

Potential energy can be calculated as follows:

  ${\text{ΔE}}_{\text{p}}=mg\Delta L$

Here, m is mass, g is acceleration due to gravity and $\Delta \text{L}$ is displacement.