Assume all other forces on Rita are balanced. Which statement describes the forces on Rita?

 - The forces are balanced, so there is no net force on Rita.
 - The forces are unbalanced, so there is a net force on Rita.
To determine if there is a net force on Rita, look at the forces:
Earth's gravity is pulling Rita down with a force of 600 N.
The seat of the cart is pushing Rita up with a force of 1,200 N.
The forces are in opposite directions, and the forces have different magnitudes: 600 N and 1,200 N. This means that the forces are unbalanced, so there is a net force on Rita.