This question involves the concepts of altitude and acceleration due to gravity.
The altitude above Earth's Surface where the acceleration due to gravity equals g/3 is "2.13 x 10⁶ m".
Variation in the value of the acceleration due to gravity with the change in altitude is given by the following formula:
[tex]g'=g(1-\frac{2h}{R_E})[/tex]
where,
Therefore,
[tex]\frac{g}{3}=g(1-\frac{2h}{R_E})\\\\ \frac{2h}{R_E}=1-\frac{1}{3}\\\\ \frac{h}{R_E}=\frac{2}{3(2)}\\\\ h=\frac{R_E}{3}=\frac{6.4\ x\ 10^6\ m}{3}[/tex]
h = 2.13 x 10⁶ m
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