The reading on the scale will be equal to the normal force exerted by the scale on the person. We can use Newton's second law of motion, which states that the net force acting on an object is equal to its mass times its acceleration:
Net force = mass x acceleration
The person's mass can be calculated using their weight, which is equal to their mass times the acceleration due to gravity (9.81 m/s^2):
Weight = mass x acceleration due to gravity
686 N = mass x 9.81 m/s^2
mass = 70 kg
Now we can use Newton's second law to find the normal force exerted by the scale:
Net force = mass x acceleration
Normal force - Weight = mass x acceleration
Normal force - 686 N = 70 kg x 4.9 m/s^2
Normal force = 1029 N
Therefore, the reading on the scale will be 1029 N. Answer: 1029 N.