What is the maximum walking speed of an adult man whose legs are each 1.2 m long? 7.9 m/s 3.4 m/s 3.6 m/s 12 m/s

To estimate the maximum walking speed of an adult man based on the length of his legs, one can use a simplified biomechanical approach considering the leg as a pendulum. The step frequency or cadence can be related to the leg length through the physics of pendulum motion. However, walking is a complex motion that can't be accurately modeled only with simple pendulum dynamics. The 'stride length' and the 'cadence' (steps per second) determine walking speed. Longer legs usually allow for a longer stride length, and theoretically, a person with longer legs might be able to walk faster.

Unfortunately, there isn't a direct formula that links leg length to maximum walking speed because it's also influenced by muscle power, coordination, and overall fitness. Empirical data suggests that the average walking speed of adults is about 1.4 m/s, and the average running speed can be up to about 6-7 m/s for trained sprinters over short distances.

Considering human limits and the fact that the speeds provided are quite high for walking and seem to enter the sprinting range, none of the options (7.9 m/s, 3.4 m/s, 3.6 m/s, 12 m/s) would be reasonable for a maximum walking speed. The closest option to plausible walking speeds would be 3.4 m/s. However, this is still quite fast for a walking speed and more into the jogging or slow running range.

So none of the provided options seem to represent realistic walking speeds; they are all too high. If we are to take the question literally and consider the speeds strictly as walking speeds, all speeds would be incorrect. But if the context is about maximum speed that can be achieved by someone while their feet still perform a walking pattern (which could extend to a power walk or even a light jog), 3.4 m/s may be considered a reasonable upper bound.