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A 95 kg person stands on a scale in an elevator. If the elevator accelerates upward with an acceleration of 2 m/s², what is the reading on the scale?

A. 950 N
B. 570 N
C. 1175 N
D. 760 N

User Jacopofar
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1 Answer

5 votes

Final answer:

The scale reading for a 95 kg person in an accelerating elevator is the normal force equal to mass times the sum of gravitational acceleration and elevator's upward acceleration, or 1121 N. Choice C is approximately correct but may have a slight calculation error as none of the options match the exact calculated value.

Step-by-step explanation:

If a 95 kg person stands on a scale in an elevator that is accelerating upward at 2 m/s², we need to calculate the reading on the scale. The scale measures the normal force that the elevator floor exerts on the person. When the elevator accelerates upward, this normal force must be greater than the gravitational force to provide the necessary upward acceleration.

The gravitational force (weight) on the person is calculated by weight (w) = mass (m) × gravity (g), where g is approximately 9.8 m/s². So the weight is:

w = 95 kg × 9.8 m/s² = 931 N

Now, we incorporate the upward acceleration (a) into the net force equation (Fnet):

Fnet = m(a + g)

Inserting the given values, we get:

Fnet = 95 kg × (2 m/s² + 9.8 m/s²) = 95 kg × 11.8 m/s² = 1121 N

This value, 1121 N, is the reading on the scale, which is the normal force acting on the person.

Looking at our answer choices, none of them exactly match our calculation. However, it's possible that choice C, which is 1175 N, could be considered approximately correct but likely contains a slight mathematical error. The exact answer calculated is not an option provided.

User Comtaler
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