A car travels at 90 km/h for 2 hours, then reduces speed to 60 km/h for the next 1.5 hours. What is the average speed for the entire journey?
["Understanding Average Speed: A Journey at 90 km/h Then 60 km/h", "When calculating how fast a car travels over a journey, it’s important to understand average speed—not just the fastest speed or simple mathematics like “total distance divided by total time.” This article explores a real-life driving scenario: a car traveling at 90 km/h for 2 hours, then slowing down to 60 km/h for 1.5 hours, and finally determining the true average speed for the entire trip.", "---", "### The Journey Breakdown", "The journey consists of two distinct segments:", "- Segment 1: 90 km/h for 2 hours\n Distance = Speed × Time = 90 km/h × 2 h = 180 km", "- Segment 2: 60 km/h for 1.5 hours\n Distance = 60 km/h × 1.5 h = 90 km", "---", "### Total Distance and Total Time", "Add up the distances and times:", "- Total distance = 180 km + 90 km = 270 km\n- Total time = 2 hours + 1.5 hours = 3.5 hours", "---", "### Calculating Average Speed", "Average speed is defined as total distance traveled divided by total time taken:", "[\n\ ext{Average speed} = \frac{\ ext{Total distance}}{\ ext{Total time}} = \frac{270, \ ext{km}}{3.5, \ ext{h}} \approx 77.14, \ ext{km/h}\n]", "Note: This value differs from simply averaging 90 km/h and 60 km/h (which gives 75 km/h), because average speed only considers total distance and total time, not the speed values themselves over the periods.", "---", "### Why Average Speed Matters", "Understanding average speed helps drivers plan journeys, estimate arrival times, and evaluate fuel efficiency. In this example, even with an initial 90 km/h stretch, reducing speed lowers the overall average, emphasizing that consistent speed isn’t always best—for efficiency and real-world conditions matter.", "---", "### Final Takeaway", "For a car traveling at 90 km/h for 2 hours and 60 km/h for 1.5 hours, the average speed over the entire journey is approximately 77.14 km/h. This illustrates why total distance and total time are critical in speed calculations, making average speed a reliable metric for real-world driving.", "If you’re driving or planning a trip, always track both speed and time to calculate accurate averages—your journey’s actual pace depends on how speed varies across segments.", "---", "### Key Terms for SEO:\naverage speed calculation, average speed over distance and time, driving journey average speed, how to calculate average speed, real driving speed example, total distance vs total time average speed, 90 km/h journey analysis, 60 km/h speed impact, travel time and speed relativity"]
