Final answer:
In an elevator accelerating upwards, the weight reading on the scale increases because the scale is pushing up on you with a force greater than your actual weight. This is due to the elevator's acceleration and can be explained by Newton's second law of motion.
Step-by-step explanation:
When you stand on a weight scale in an elevator that is accelerating upwards, you observe an increase in your weight. This is because the scale is pushing up on you with a force greater than your actual weight to accelerate you upward. The greater the acceleration of the elevator, the greater the scale reading on the weight scale. This can be understood by considering Newton's second law of motion, which states that the force exerted on an object is equal to the mass of the object multiplied by its acceleration. In this case, the force reading on the scale is the sum of your actual weight and the force necessary to accelerate you upward.