Assume all other forces on Reba are balanced. Which statement describes the forces on Reba?
A: The forces are unbalanced, so there is a net force on Reba.
B: The forces are balanced, so there is no net force on Reba.
To determine if there is a net force on Reba, look at the forces:
Earth's gravity is pulling Reba down with a force of 600 N.
The seat of the cart is pushing Reba 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 Reba.