please show the working out of how the 48.6 m is acheived.

( 400.9 m^4 s^-3 ) /
( 5 m s^-1 x 0.0007 s^-2 )1/3

= 48.6 m

I haven't worked through the numbers but the units work out as

[(m^4 s^-3)/(m s^-1 s^-2)]^1/3

cancel the m

[(m^3 s^-3)/(s^-1 s^-2)]^1/3

combine s^-1 and s^-2

[(m^3 s^-3)/(s^-3)]^1/3

cancel the s^-3

[(m^3)]^1/3

cube root of m^3 is m