Answer
(a) The person can lift a weight of 1740 N
(b) The person's applied force can lift the larger weight in the wheelbarrow because the person's force is applied at a greater distance from the axis of rotation. Note that the ground also pushes up on the wheelbarrow with a force.
Work Step by Step
(a) Let $W$ be the weight of the material in the wheelbarrow. Let's consider an axis of rotation at the position of the wheel's axle.
$\sum \tau = 0$
$W~(0.50~m)+(80.0~N)(0.50~m) - (650~N)(1.4~m) = 0$
$W~(0.50~m)= (650~N)(1.4~m)-(80.0~N)(0.50~m)$
$W = \frac{(650~N)(1.4~m)-(80.0~N)(0.50~m)}{0.50~m}$
$W = 1740~N$
The person can lift a weight of 1740 N.
(b) The person's applied force can lift the larger weight in the wheelbarrow because the person's force is applied at a greater distance from the axis of rotation. Note that the axle also pushes up on the wheelbarrow's bowl with a force that keeps the vertical forces in equilibrium.
