Total energy (kinetic plus potential) must be conserved between the top and bottom of the hill. Because the sled starts from rest, and potential energy is zero at the bottom of the hill, PE_initial=KE_final
m*g*h=0.5*m*v^2
where m is mass, 54.6 kg
g is gravitational acceleration, 9.81 m/s^2
h is height, 8.97 m
and v is final velocity
rearranging: v=sqrt(g*h*2)=13.3 m/s
