To determine the average velocity of the car for the entire trip, we need to follow a systematic approach. Let's break it down step-by-step. ### Step 1: Understand the Concept of Average Velocity Average velocity is defined as the total displacement divided by the total time taken. Displacement is the straight-line distance from the starting point to the final position, along with the direction. ### Step 2: Calculate Total Displacement 1. **First Leg of the Trip**: The car travels 150 kilometers north. 2. **Second Leg of the Trip**: The car then travels 50 kilometers south. To find the total displacement: - Start at the origin (0 km). - After the first leg, the position is +150 km (north). - After the second leg, the position is +150 km - 50 km = +100 km (north). Thus, the total displacement is **100 kilometers north**. ### Step 3: Calculate Total Time 1. **Time for the First Leg**: 2 hours. 2. **Time for the Second Leg**: 1 hour. Total time taken = 2 hours + 1 hour = **3 hours**. ### Step 4: Calculate Average Velocity Now, we can calculate the average velocity using the formula: \[ \text{Average Velocity} = \frac{\text{Total Displacement}}{\text{Total Time}} \] Substituting the values we found: \[ \text{Average Velocity} = \frac{100 \text{ km (north)}}{3 \text{ hours}} \approx 33.33 \text{ km/h (north)} \] ### Conclusion The average velocity of the car for the entire trip is approximately **33.33 km/h north**. Therefore, the correct answer is **D. 33.33 km/h north**. ### Explanation of Other Options - **A. 50 km/h north**: This option is incorrect because it does not take into account the total displacement and total time correctly. It seems to be an average speed calculation rather than average velocity. - **B. 100 km/h north**: This option is also incorrect. It suggests that the car would have traveled 100 km in 1 hour, which is not the case since the total time is 3 hours. - **C. 25 km/h south**: This option is incorrect as it suggests a southward average velocity, which contradicts the net displacement being north. ### Common Pitfalls - Confusing average speed with average velocity: Average speed is total distance divided by total time, while average velocity considers direction. - Not accounting for direction when calculating displacement: Always remember that displacement is a vector quantity, which means it has both magnitude and direction. ### Revision Summary - Average velocity = Total displacement / Total time. - Displacement is the straight-line distance from start to finish, considering direction. - For this problem, total displacement is 100 km north, and total time is 3 hours. - The average velocity is approximately 33.33 km/h north.