Achild has legs that are each 0.500 m long. what is her maximum walking speed?

a. 2.21 m/s
b. 2.19 m/s
c. 2.6 m/s
d. 5.58 m/s

If a child has legs of length 0.500m long, to calculate the maximum walking speed, use this formula:
s=√gl
s=walking speed, g=acceleration due to gravity that is 9.8m/s2 and l is the length of legs which is 0.500m
so,
s=√(9.8)(0.500)
s=√4.9
s=2.21m/s 
so  A is the correct option, her maximum walking speed is 2.21 m/s.