Solving the Elevator Problem: Weight, Speed & Acceleration

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SUMMARY

The discussion focuses on calculating the weight reading on a scale when a 56-kg girl stands in an elevator ascending at 13 m/s while decelerating at 4 m/s². Using Newton's second law, the effective weight can be determined by combining the gravitational force with the force due to the elevator's deceleration. The acceleration is directed opposite to the elevator's velocity, leading to the formula W = mg + ma_elevator, where 'm' is mass, 'g' is gravitational acceleration, and 'a_elevator' is the elevator's deceleration.

PREREQUISITES
  • Understanding of Newton's second law of motion
  • Basic knowledge of acceleration and its direction
  • Familiarity with weight calculations in physics
  • Ability to apply kinematic equations
NEXT STEPS
  • Learn how to calculate acceleration using the formula a = Δv/Δt
  • Study the effects of deceleration on weight measurements in varying contexts
  • Explore the implications of forces in non-inertial reference frames
  • Investigate real-world applications of Newton's laws in elevator systems
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Students studying physics, educators teaching mechanics, and engineers designing elevator systems will benefit from this discussion.

khf
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A 56-kg girl weighs herself by standing on a scale in an elevator. What does the scale read when the elevator is ascending at 13m/s buts its speed is decreasing by 4m/s in each second?

I know you use Newton's second law, however, I do not know how to find acceleration..
 
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which direction is the acceration? If you figure that out you know which direction the force of the slowing elevator is. Add the wieght vector with the force vector to get her wieght...




the acceration if opposite the velocity ( girl weighs W = mg + ma_elevator)
 
khf said:
I know you use Newton's second law, however, I do not know how to find acceleration..
Apply the definition of acceleration: [itex]a = \Delta v/\Delta t[/itex]. (Direction matters.)
 

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