A car travels at a constant speed of 60 km/h for 2.5 hours. How far does it travel, and what is its average speed if it returns at 80 km/h?
["How Far Does a Car Travel at Constant Speed? A Practical Example with Average Speed", "When analyzing distance, speed, and time in travel, a classic problem involves a car moving at a constant speed for a set duration, then returning at a different speed. Understanding the total distance and average speed helps clarify fundamental physics and daily commuting calculations — whether you’re commuting, planning a road trip, or working on physics problems. In this article, we explore a real-world scenario: a car traveling at a constant 60 km/h for 2.5 hours, followed by a return journey at 80 km/h. We’ll calculate the total distance traveled and determine the average speed for the entire round trip.", "---", "### Step 1: Distance Traveled at Constant Speed", "The first leg of the journey involves a car moving at a steady speed of 60 km/h for 2.5 hours.", "Using the basic formula for distance:\nDistance = Speed × Time", "[\n\ ext{Distance}_1 = 60,\ ext{km/h} \ imes 2.5,\ ext{h} = 150,\ ext{km}\n]", "So, the car travels 150 kilometers in the outward journey.", "---", "### Step 2: Return Journey at 80 km/h", "On the return trip, the car travels the same distance — 150 km — but at a higher speed of 80 km/h. This allows us to calculate the time taken for the return leg:", "[\n\ ext{Time}_2 = \frac{\ ext{Distance}}{\ ext{Speed}} = \frac{150,\ ext{km}}{80,\ ext{km/h}} = 1.875,\ ext{h} = 1,\ ext{hour and},52.5,\ ext{minutes}\n]", "---", "### Step 3: Total Distance of the Round Trip", "The total distance traveled is the sum of both legs:", "[\n\ ext{Total Distance} = 150,\ ext{km} + 150,\ ext{km} = 300,\ ext{km}\n]", "---", "### Step 4: Total Time of the Trip", "Add the travel times:", "[\n\ ext{Total Time} = 2.5,\ ext{h} + 1.875,\ ext{h} = 4.375,\ ext{hours}\n]", "---", "### Step 5: Calculating Average Speed", "Average speed is defined as total distance divided by total time:", "[\n\ ext{Average Speed} = \frac{\ ext{Total Distance}}{\ ext{Total Time}} = \frac{300,\ ext{km}}{4.375,\ ext{h}} = 68.57,\ ext{km/h} \quad (\ ext{approx.})\n]", "Alternatively, average speed for round trips with equal distances but different speeds can be calculated via:\n[\n\ ext{Average Speed} = \frac{2 \ imes D_1 \ imes D_2}{D_1 + D_2} \ imes \frac{D_1 + D_2}{T_1 + T_2}\n]\nBut in this exact case, direct division gives the most precise value: ≈68.57 km/h", "---", "### Why This Matters", "Knowing how to compute distance, travel time, and average speed is valuable in many areas:", "- Travel planning: Estimating arrival times and fuel needs.\n- Physics education: Reinforces concepts of motion, velocity, and harmonic averaging.\n- Transport efficiency: Helps logistics and commuters understand performance metrics.", "---", "### Summary", "- At 60 km/h for 2.5 hours, a car travels 150 km.\n- Returning at 80 km/h over the same distance takes 1.875 hours (1 hour 52.5 minutes).\n- Total distance: 300 km\n- Total time: 4.375 hours\n- Average speed: ≈68.57 km/h", "Understanding these principles transforms complex voyages into predictable journeys — making travel planning smarter and more efficient.", "---", "Keywords: car speed, distance calculation, average speed, physics problem, travel distance, average velocity, road trip calculation, constant speed motion, kinetic motion, travel time, speed and time, motion speed average, round trip average speed."]
