-- As far as we know, the forces on the wheelbarrow are balanced.
-- That tells us that the net force on the wheelbarrow is zero, just
as if there were no forces acting on it at all.
-- That tells us that the wheelbarrow's acceleration is zero ... its
speed and direction of motion are not changing.
-- That tells us that the wheelbarrow is moving in a straight line
at a constant speed. It's very possible that relative to us, the speed
may be zero, but we can't tell that from the given information.
