Final answer:
The reading on the scale will be greater than the actual weight of a person while weighing himself on a spring scale in an elevator that is accelerating upward.
Step-by-step explanation:
When a former student of mechanics weighs himself in an elevator that is accelerating upward, the scale will show a reading that is greater than his actual weight. This is because when the elevator accelerates upwards, the scale must exert an additional force to overcome both the gravitational force and provide the extra force required to accelerate the person upwards in accordance with Newton's second law of motion. The formula for net force on the person in the accelerating elevator is Fnet = ma = Fs - mg, where Fs is the scale force, mg is the weight, m is the mass, and a is the acceleration. When the elevator is at a constant upward velocity, the acceleration is zero, so the scale force equals the person's weight, Fs = mg.
Newton’s second law of motion, unlike the first law of motion, pertains to the behaviour of objects for which all existing forces are unbalanced. The second law of motion is more quantitative and is used extensively to calculate what happens in situations involving a force
However, in the scenario of the elevator accelerating upward, the person's apparent weight, as indicated by the scale reading, is due to the sum of the true weight and the additional force required to accelerate the person. Hence, the reading is greater than the actual weight. Therefore, the answer is A) Greater than his actual weight.