Chapter 3, Problem 40P

To determine

Time pilots have to take an action.

Answer to Problem 40P

The pilots have 25.56 sec to take action.

Explanation of Solution

Given:

The two planes have velocity 785 km/hr [218.05 m/s] and 11 km apart

  $v_p=218.08\text{ m/s}$

Formula Used:

  $\begin{array}{l}\text{Relative velocity of plane = }\frac{\text{distance}}{\text{time}}\\ v_R=\frac{d}{t}\\ v_R=v_p+u_p\end{array}$

Calculation:

Substituting the values in equation

  $\begin{array}{l}{v}_R=218.08+218.05\\ v_R=436.1\text{ m/s}\end{array}$

Substituting the values in equation

  $\begin{array}{l}436.1=\frac{1100}{t}\\ t=\frac{11000}{436.1}\\ t=25.56\text{ sec}\end{array}$

Conclusion:

Thus, the pilots have 25.56 sec to take action.