Question

How to calculate relative speed of two cars

Answer 1

To calculate the relative speed of two cars, you can follow these steps:

1. **Define the Speeds**: First, you need to know the speed of each car. Let’s say:
- Speed of Car A = \( v_A \) (in km/h or m/s)
- Speed of Car B = \( v_B \) (in km/h or m/s)

2. **Determine their Directions**: The relative speed depends on the direction the cars are moving:
- If the cars are moving in the **same direction**, the relative speed is calculated by subtracting their speeds:
\[
\text{Relative Speed} = |v_A - v_B|
\]
- If the cars are moving in **opposite directions**, the relative speed is the sum of their speeds:
\[
\text{Relative Speed} = v_A + v_B
\]

### Example 1: Same Direction
- Car A is moving at 60 km/h and Car B at 50 km/h.
- The relative speed:
\[
\text{Relative Speed} = |60 - 50| = 10 \text{ km/h}
\]

### Example 2: Opposite Directions
- Car A is moving at 60 km/h and Car B at 50 km/h, but in opposite directions.
- The relative speed:
\[
\text{Relative Speed} = 60 + 50 = 110 \text{ km/h}
\]

### Summary
- **Same direction**: \( |v_A - v_B| \)
- **Opposite direction**: \( v_A + v_B \)

Make sure to keep consistent units when performing your calculations!