1. What is Average Speed When 2 Speeds Are Given?

Definition: This calculator computes the harmonic mean of two speeds, which is the correct way to calculate average speed when equal distances are traveled at different speeds.

Purpose: It helps determine the true average speed for trips where you travel equal distances at two different speeds (like going to and from a destination at different speeds).

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( AS \) — Average speed (mph)
• \( S1 \) — First speed (mph)
• \( S2 \) — Second speed (mph)

Explanation: This harmonic mean formula accounts for the fact that more time is spent traveling at the lower speed when covering equal distances.

3. Importance of Correct Average Speed Calculation

Details: Using the arithmetic mean (simple average) would overestimate your actual average speed. This formula gives the true time-weighted average.

4. Using the Calculator

Tips: Enter both speeds in mph. Both values must be > 0. The result is the accurate average speed for the entire trip.

5. Frequently Asked Questions (FAQ)

Q1: Why not just average the two speeds?
A: The arithmetic average only works when equal time is spent at each speed. For equal distances, the harmonic mean is correct.

Q2: Does this work for more than two speeds?
A: For multiple speeds over equal distances, use the generalized harmonic mean: \( AS = \frac{n}{\frac{1}{S1} + \frac{1}{S2} + ... + \frac{1}{Sn}} \)

Q3: What if I traveled different distances?
A: For different distances, calculate total distance divided by total time.

Q4: Can I use different units (km/h)?
A: Yes, as long as both speeds use the same units, the result will be in those units.

Q5: When is this formula most useful?
A: Particularly useful for round trips where you travel the same route at different speeds.