Why do you need to apply a force in order to get the box to move

The reason one must apply a force to a box in order for the box to move is to overcome the friction generated by the box against the plane the box is sitting.

The box at rest has zero friction against the surface on which it sits.  Once a force is applied, a box's movement is resisted by the friction created from contact with the surface.

In order for the box to move, one must generate more force than is being generated by the friction of the surface onto the box, allowing the box to move.

Cheers.

1gm = 1000mg so 0.1gm = 1000mg

first, convert the weight to kg

160lb * 1kg/2.2lb = 72.7kg

next, the dose

72.7kg * 100mg/kg = 7270mg

δabc ≅ δdcb by sas because

db ≅ ac . . given (side)

bc ≅ bc . . reflexive property (side)

∠dbc ≅ ∠ acb . . alternate interior angles where transversal bc crosses parallel lines bd and ac (included angle)