B(12 Points) Two cars start moving from the same point. One travels west at 35 mph and
the other travels south at
20 mph. At what rate is the distance between the cars
increasing 2 hours later
? Round to the nearest tenth and label appropriately.



Answer :

Sure, let's break down the solution step-by-step.

Step 1: Define the scenario and initial speeds of the cars.
- One car travels west at a speed of 35 mph.
- The other car travels south at a speed of 20 mph.

Step 2: Calculate the distances traveled by each car after 2 hours.
- Distance traveled by the car moving west: [tex]\( \text{distance}_\text{west} = \text{speed}_\text{west} \times \text{time} = 35 \text{ mph} \times 2 \text{ hours} = 70 \text{ miles} \)[/tex]
- Distance traveled by the car moving south: [tex]\( \text{distance}_\text{south} = \text{speed}_\text{south} \times \text{time} = 20 \text{ mph} \times 2 \text{ hours} = 40 \text{ miles} \)[/tex]

Step 3: Determine the distance between the two cars after 2 hours.
- Since the cars are moving perpendicularly to each other, we can use the Pythagorean theorem.
- Let [tex]\( d \)[/tex] be the distance between the two cars.
- [tex]\( d = \sqrt{ \text{distance}_\text{west}^2 + \text{distance}_\text{south}^2 } = \sqrt{ 70^2 + 40^2 } \approx 80.6 \text{ miles} \)[/tex]

Step 4: Find the rate at which the distance between the cars is increasing.
- To find the rate at which the distance between the two cars is increasing, we use differentiation.
- Given that speed_west and speed_south are constants, the rate of increase of the distance between the two cars is given by:

- [tex]\(\text{rate of increase} = \sqrt{ \text{speed}_\text{west}^2 + \text{speed}_\text{south}^2 } = \sqrt{ 35^2 + 20^2 } \approx 40.3 \text{ mph} \)[/tex]

So, 2 hours later, the distance between the cars is increasing at a rate of approximately 40.3 mph.