Find the direction of acceleration

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SUMMARY

The discussion revolves around calculating the acceleration of an elevator based on the reading of a bathroom scale. When the elevator begins to move, the scale reads 0.66 times the person's weight, indicating a downward acceleration. Using the equation N - 0.66mg = 0.66ma, the user deduces that the acceleration is negative, confirming the downward motion of the elevator. The final equation simplifies to -0.66 = ma, allowing for the calculation of acceleration once mass is factored out.

PREREQUISITES
  • Understanding of Newton's Second Law (F = ma)
  • Knowledge of free body diagrams
  • Familiarity with normal force and gravitational force concepts
  • Basic algebra for solving equations
NEXT STEPS
  • Study the concept of normal force in varying acceleration scenarios
  • Learn how to derive equations of motion for objects in elevators
  • Explore the implications of weightlessness and apparent weight in different gravitational contexts
  • Investigate the effects of acceleration on forces in non-inertial reference frames
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Students studying physics, particularly those focusing on mechanics and forces, as well as educators looking for practical examples of Newton's laws in action.

Mustachio
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Homework Statement



A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.66 of the person's regular weight. Calculate the acceleration of the elevator, and find the direction of acceleration.

Homework Equations



So I know you have to use sumF = MA to solve this problem.

The Attempt at a Solution



I drew a freebody diagram.
^
|
| Fn
.
|
| .66mg
V

And I got the formula N - .66mg = .66ma. This where I get stuck. I don't know what to do next.

As for the second part of the question, I know that the elevator is moving downward because of the decrease in mass.
 
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The normal force is 0.66mg and the person's weight is mg.
 


So I took that into account and got

.66mg - mg = .66ma
-.44 = .66ma
-.66 = ma.

Now I don't know what to do with the m. :\
 


The mass is considered to still be m on the right side of the equation. Also, 0.66mg - mg = -0.34mg.
 


Thank you. I feel very stupid right now for not noticing that arithmetical mistake.
 

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