Forces, elevator, acceleration -- I have the answer, just explain it....

AI Thread Summary
When a 45-kg person stands on a scale in an elevator reading 480 N, the gravitational force is calculated as 441 N. This indicates that the scale reading is greater than the weight, suggesting the elevator is accelerating upward. The discussion clarifies that the elevator could be moving upward at a constant rate or accelerating upward, but it is impossible to determine the direction of movement solely from the scale reading. Therefore, both options A (elevator accelerating upward) and E (uncertainty about direction) are correct. Understanding the distinction between velocity and acceleration is crucial in this context.
PhysicsStudent1
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Homework Statement


When a 45-kg person steps on a scale in an elevator, the scale reads a steady 480 N. Which of the following statements must be true? There could be more than one correct choice.
a) The elevator is accelerating upward at a constant rate
b) The elevator is moving downward at a constant rate
c) The elevator is moving upward at a constant rate
d) The elevator is accelerating downward at a constant rate
e) From the given information, we cannot tell if the elevator is moving up or down

Homework Equations


F = ma
Fg = mg

The Attempt at a Solution


From the equation, I know that the Fg is (45)(9.8) = 441.
I think the answer is a. But my textbook says that it is both A and E. Can someone help explain why? Thanks in advance :)
 
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PhysicsStudent1 said:
I think the answer is a. But my textbook says that it is both A and E. Can someone help explain why?
Hint: "moving up or down" refers to velocity, not acceleration. What's the difference?
 
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oh ok gotcha thank you :)
 
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