Final answer:
The normal force on a 5.0 kg dog in a downward accelerating elevator at 2.0 m/s² is 39.05 N, calculated by subtracting the force due to acceleration from the dog's weight.
Step-by-step explanation:
The magnitude of the normal force of the elevator floor on a 5.0 kg dog accelerating downward at 2.0 m/s² can be found using Newton's second law of motion. The normal force can be figured out by subtracting the force due to the acceleration from the dog's weight. The force due to acceleration is mass times acceleration (m×a), which is 5.0 kg × 2.0 m/s² = 10 N. The weight of the dog, which is the force due to gravity, is found by multiplying the mass by the acceleration due to gravity (9.81 m/s²), giving us 5.0 kg × 9.81 m/s² = 49.05 N. Therefore, the normal force is 49.05 N - 10 N = 39.05 N.