Answer:
the mass of the child is not given and the question is not complete
but heres the solution.
Using the law of conservation of energy
Initial gravitational energy = work done by friction + work done gained by kinetic energy
mgh = w + 0.5m[tex]v^{2}[/tex]
w =29kg ×9.8m.[tex]s^{-2}[/tex] ×13m - 0.5×29kg×1.70m.[tex]s^{-1}[/tex]
w =3669.95 J
Explanation: