The work done by a force is given by W = Fdcosθ where F = force applied and d = distance moved and θ is the angle between the force and distance moved.
Here, F = frictional force = 14.2 N
d = distance = 13.5 m
and θ = 180° since the direction of the frictional force and distance are opposite.
If someone is underground, then therefore there is less planet/ground underneath them, so there would be less gravity. Gravity directly affects weight.
