A wheelbarrow is a second class lever.
The Class of Lever is determined by the location of the load, fulcrum, and force.
In a Class Two Lever such as the wheelbarrow, the Load is between the Force and the Fulcrum.
The closer the Load is to the Fulcrum, the easier the load is to lift.
Examples of the second class levers include wheelbarrows, staplers, bottle openers, nut cracker, and nail clippers.
A wheelbarrow is a second class lever. Below is data from using a wheelbarrow to move a 30 kg rock.
The effort (lift) is always applied at the end of the handles, 150 cm from the fulcrum.
The fulcrum is where the wheelbarrow is joined to the axle of the wheel.
The dirt in a wheelbarrow is the Load, the Fulcrum is the wheel, and the Force is at the end of the handles where a person lifts it.
When the dirt is spread out evenly, the wheelbarrow is balanced and not difficult to push and move from place to place.