Chapter 9.6, Problem 1P

To determine

Tofind:the equation of the row boat if its travelling downstream.

Answer to Problem 1P

The equation can be written as $\text{r+c}$ = $\text{15}\text{km}/\text{h}$ .

Explanation of Solution

Given:

  $\text{r}$ is rate in $\text{km}/\text{h}$ of the row boat in still water.

  $\text{c}$ is rate in $\text{km}/\text{h}$ of the current.

Concept used:

If the thing is going against the gravity is taken as $\text{-ive}$ .

According to the Vector formula:

  ${\text{R}}^2{\text{=A}}^{\text{2}}{\text{+B}}^{\text{2}}\text{+2ABcosθ}$ .

If the direction of any against the gravity means it make ${\text{180}}^0$ so $\cos \left({180}^0\right)=-1$ .with the gravity.

  ${\text{R}}^2{\text{=A}}^{\text{2}}{\text{+B}}^{\text{2}}\text{-2AB}$ .

  $\text{R=A-B}$ .

Calculation:

Travelling downstream is $\text{r+c}$ if the rate travelling downstream is $\text{15}\text{km}/\text{h}$ .

Then $\text{r+c}$ = $\text{15}\text{km}/\text{h}$ .

Hence the equation can be written as $\text{r+c}$ = $\text{15}\text{km}/\text{h}$ .