Explanation:
The forces acting on the sled are the following:
Fg = force of gravity acting downward
Fn = normal force acting upward
Fa = the force applied by you
Ff = force of friction slowing the sled down.
All these forces are shown in the sketch below.
For a person hanging from a bungee cord, only two forces are present:
FT = force applied by the cord on the person.
Fg = force of gravity acting downward.
These two forces acting on the person are shown in the sketch below.
