The time taken by the sled to reach 45 m to the bottom is 4.24 s.
The sled's initial velocity u is zero. It has an acceleration a of a value 5 m/s² down the hill and it travels a distance s equal to 45 m down the hill.
Use the equation of motion,
[tex]s=ut+\frac{1}{2} at^2[/tex]
Substitute 0 m/s for u and rewrite the equation for t.
[tex]t=\sqrt{\frac{2s}{a}} \\ =\sqrt{\frac{2(45 m)}{5.0m/s^2} } \\ =4.24s[/tex]
The sled takes a time of 4.24 s to reach the bottom of the hill