Question

a student wants to conduct a series of trials to know what happens to his weight when he jumps upward off a common bathroom scale. to prepare for his several trials, he first conducts a test jump, and his lab partner observes the scale reading. which statement describes the scale reading during the test jump? the scale reading will remain unchanged. the scale reading will increase momentarily and then will decrease as the student is moving upward. the scale reading will increase during the entire jump. the scale reading will decrease momentarily and then will increase as the student is moving upward.

Explanation:

Step1: Analyze the initial phase

When the student starts to jump, they accelerate upward. According to Newton's second - law $F_{net}=ma$, the normal force $N$ (scale reading) must be greater than the weight $mg$ to provide the upward acceleration. So the scale reading increases momentarily.

Step2: Analyze the upward - moving phase

Once the student leaves the scale and is moving upward, they are in free - fall (neglecting air resistance). In free - fall, the only force acting on the student is gravity, and the normal force from the scale is zero. So the scale reading decreases as the student moves upward.

Answer:

The scale reading will increase momentarily and then will decrease as the student is moving upward.