Chapter 3, Problem 47P

(a)

To determine

The landing distance.

Answer to Problem 47P

66.67 m.

Explanation of Solution

Given:

  $\begin{array}{l}\text{Velocity of swimmer is }{v}_s=0.45\text{ m/s}\\ \text{Wide of river, }w=75\text{ m}\\ \text{Velocity of river, }{v}_R=0.40\text{ m/s}\end{array}$

Formula Used:

  $\begin{array}{l}\text{Time take to cross river = }\frac{\text{Width of river}}{\text{Speed of swimmer}}\\ t=\frac{w}{v_s}\\ \text{Drift = Velocity of river × time}\\ d=v_R\times t\end{array}$

Calculation:

Substituting the given value

  $t=\frac{75}{0.45}=166.67\text{ sec}$

Substituting the given value

  $\begin{array}{l}d=0.40\times 166.67\text{ sec}\\ d=66.67\text{ m}\end{array}$

Conclusion:

Therefore the drift is 66.67 m.

(b)

To determine

Time taken to reach other side.

Answer to Problem 47P

166.67 sec

Explanation of Solution

Given:

  $\begin{array}{l}\text{Width of river, }w=75\text{ m}\\ \text{Velocity of swimmer, }{v}_s=0.45\text{ m/s}\end{array}$

Formula Used:

  $\begin{array}{l}\text{time = }\frac{\text{width of river}}{\text{speed of swimmer}}\\ t=\frac{w}{v_s}\end{array}$

Calculation:

Substituting the value

  $\begin{array}{l}t=\frac{75}{0.45}\\ t=166.67\text{ sec}\end{array}$

Conclusion:

The time take to reach other side 166.67 sec.