The square root is trying to find the number that goes into it twice.
[tex] \sqrt{49} = 7 \\ 7 \times 7 = 49 \\ {7}^{2} = 49[/tex]
but the cube root of a number is what number goes into it 3 times
[tex] \sqrt[3]{8} = 2 \\ 2 \times 2 \times 2 = 8 \\ {2}^{3} = 8[/tex]