Chapter 7, Problem 7.7P

Interpretation Introduction

(a)

Interpretation:

The amount of potential energy $\left(\text{ft}\cdot {\text{lb}}_{\text{f}}\right)$ lost by water for the given data is to be calculated.

Concept introduction:

A system contains mainly three forms of energy; kinetic energy, potential energy and internal energy. Kinetic energy is related to the translational motion of the system with respect to the some reference (mostly earth). Potential energy is related to the position of system in a potential field. Internal energy is related to all energy other than potential and kinetic.

Interpretation Introduction

(b)

Interpretation:

The speed of water travelling just before impact is to be calculated.

Concept introduction:

Moving water contains energy in the form of kinetic energy, which is equal to the potential energy (just before impact). This relation is expressed as,

$\begin{array}{c}{\stackrel{·}{E}}_{\text{p}}={\stackrel{·}{E}}_{\text{k}}\\ {\stackrel{·}{E}}_{\text{p}}=\frac{1}{2}\stackrel{·}{m}{u}^2\end{array}$

Interpretation Introduction

(c)

Interpretation:

The given statement that “Energy must be conserved, therefore the kinetic energy before impact must equal to the kinetic energy of the cat after impact” is to be authenticated and if it is false the change that would have happened with most of the kinetic energy that the water possessed just before impact is to be stated.

Concept introduction:

A system contains mainly three forms of energy; kinetic energy, potential energy and internal energy. Kinetic energy is related to the translational motion of the system with respect to the some reference (mostly earth). Potential energy is related to the position of system in a potential field. Internal energy is related to all the energy other than potential and kinetic.