Question

Two boats leave the same place at the same time. The first boat heads due north at 10 kilometers per hour. The second boat heads due west at 16 kilometers per hour. After 2.5 hours, how fast is the distance between the boats increasing

Answer 1

Answer:

18.87 km/hr

Step-by-step explanation:

First boat is heading North with a speed of 10 km/hr.

Second boat is heading West with a speed of 16 km/hr.

Time for which they move = 2.5 hours

To find:

The speed at which the distance is increasing between the two boats.

Solution:

Let the situation be represented by the attached diagram.

Their initial position is represented by point O from where they move towards point A and point B respectively.

$Distance = Speed \times Time$

$Distance\ OA = 10 \times 2.5 = 25\ km$

$Distance\ OB = 16 \times 2.5 = 40\ km$

We can use Pythagorean Theorem to find the distance AB.

AB is the hypotenuse of the right angled $\triangle AOB$.

According to Pythagorean theorem:

$\text{Hypotenuse}^{2} = \text{Base}^{2} + \text{Perpendicular}^{2}\\\Rightarrow AB^{2} = OA^{2} + OB^{2}\\\Rightarrow AB^2 = 25^2 + 40^2\\\Rightarrow AB^2 = 2225^2\\\Rightarrow AB^2 \approx 47.17\ km$

The speed at which distance is increasing between the two boats is given as:

$\dfrac{47.17}{2.5} \approx 18.87\ km/hr$