Force Diagram, Position vs Time Plot: Construct, Calculate, Sketch

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SUMMARY

The discussion focuses on analyzing the vertical motion of an elevator through a Position vs Time plot. Key tasks include constructing a Velocity vs Time plot, calculating average acceleration between t = 8.0s and t = 10s, sketching a force diagram for a 70 kg occupant, and determining the Normal force (FN). The calculated average acceleration is -0.7 m/s2, and the Normal force is incorrectly computed as -163.10 N, indicating a misunderstanding of the force diagram requirements.

PREREQUISITES
  • Understanding of kinematics, including Position vs Time and Velocity vs Time plots.
  • Knowledge of Newton's second law of motion and force calculations.
  • Familiarity with basic concepts of acceleration and its calculation.
  • Ability to sketch force diagrams and interpret physical scenarios.
NEXT STEPS
  • Learn how to construct Velocity vs Time plots from Position vs Time data.
  • Study the principles of calculating acceleration in various motion scenarios.
  • Research how to accurately sketch force diagrams, including all acting forces.
  • Explore the correct application of Newton's laws to determine Normal force in different contexts.
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Students in physics, educators teaching kinematics, and anyone involved in analyzing motion and forces in mechanical systems.

BrownBoi7
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The vertical motion of an elevator is recorded and a Position vs Time plot is generated. The plot is shown in the image attached.


1. Construct a scale drawing of the associated Velocity vs Time plot complete with axis labels.

2. Calculate the average acceleration for the time interval t =8.0s to t = 10s.

3. Sketch a force diagram of an elevator occupant with a mass of 70 kg during the time interval t =8.0s to t = 10s.

4. Calculate the Normal force F N of the occupant using the acceleration you calculated in part 2

Can somebody please tell me where I went wrong? Thanks!

Mt attempt:
1. Velocity during 0 to 10 = 14 m / 10 s = 1.4 m/s
Velocity during 10 to 19 = 0 m/s
Velocity during 19 to 25 = -14 m /6 s = - 2.33 m/s

2. a = delta v/delta t = 0 - 1.4 m/s/2 s = -0.7 m/s^2

3. I have no clue. How do you figure this one out?

4. Fn = 70 kg * -2.33 m/s^2 = -163.10 N
 

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  • p vs t graph.JPG
    p vs t graph.JPG
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3. you know the mass and the acceleration, so you know the force for the asked interval.
 
Yea but apparently my answers to other questions are also wrong. I don't know what's the problem. And 3 is asking for a force sketch.
 

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