Final answer:
The elevator car is most likely moving upward at an increasing speed when a bathroom scale shows a value greater than a student's normal weight because the elevator must accelerate upwards, resulting in a net upward force on the student.
Step-by-step explanation:
When a person standing on a bathroom scale in an elevator sees a reading greater than their normal weight, it indicates that the elevator is exerting an additional force to accelerate the person. If the elevator car is most likely moving upward at an increasing speed (accelerating upwards), the scale will read a value greater than the weight of the student at rest. This is because the acceleration results in a net force acting upwards on the student, which is the sum of the gravitational force (their weight) and the force from the elevator floor (the scale reading).
On the other hand, if the elevator is moving upward at a constant speed, the scale would not read more than the student's normal weight, since there is no acceleration (Newton's first law of motion), and the only force acting on the student is due to gravity, which is balanced by the normal force from the scale.