Final answer:
In an elevator with upward acceleration a, a cardboard box of mass m rests on the floor. The normal force acting on the box will be greater than its weight due to the upward acceleration of the elevator.
Step-by-step explanation:
In the given situation, the elevator is experiencing an upward acceleration, denoted as a. A cardboard box with mass m is resting on the floor of the elevator.
When an elevator accelerates upwards, the apparent weight of objects inside the elevator increases. The normal force acting on the cardboard box will be greater than its weight. This can be understood using the equation:
Fn = mg + ma
where Fn is the normal force, m is the mass of the box, g is the acceleration due to gravity, and a is the upward acceleration of the elevator. The value of Fn increases with the acceleration of the elevator.