Terminal Velocity: Student Investigation & Incorrect Book Answer

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Discussion Overview

The discussion revolves around the concept of terminal velocity, specifically in the context of a student investigation involving parachutes of varying sizes attached to steel balls. Participants are examining how the size of the parachute affects the forces acting on the balls during freefall and questioning the correctness of an answer provided in a textbook regarding the speed of the ball with the largest parachute compared to others at terminal velocity.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant believes the book's answer is incorrect, suggesting that a larger parachute should result in a slower terminal velocity for the ball.
  • Another participant questions whether all the balls are of the same mass, indicating that mass could influence the outcome.
  • Some participants agree that given identical steel balls, the ball with the larger parachute should have a slower terminal velocity, although they note that the wording of the question may complicate this understanding.
  • One participant shares personal experience, stating that they have always found parachutes to slow them down and that a smaller parachute resulted in a faster fall compared to a larger one.
  • There is speculation about the exact wording of the question in the book, with one participant suggesting that the question may have been misinterpreted or incorrectly transcribed.
  • Another participant asserts that the question seems acceptable and reiterates that the ball with the largest parachute will be traveling more slowly than those with smaller or no parachutes at terminal velocity.

Areas of Agreement / Disagreement

Participants express disagreement regarding the correctness of the textbook answer, with some asserting it is wrong while others seek clarification on the question's wording. There is no consensus on the interpretation of the question or the implications of the parachute size on terminal velocity.

Contextual Notes

Participants note the importance of context in understanding the question, and there is uncertainty regarding the exact phrasing found in the book, which may affect interpretations of the problem.

Barclay
Messages
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This is not a homework question. It is basic physics.

The question in the book relates to terminal velocity. I think the answer in the book is incorrect. Please advise.

Students are investigating how the area of a parachute affects the forces acting on it in freefall. Steel balls are attached to parachutes of varying sizes and then dropped from a fixed height, timing how long it takes to hit the ground.

Then the book asks a question:

Question: will the ball with the largest parachute will be traveling more quickly or more slowly than other balls traveling at terminal velocity?

I think the answer should be slowly but the book says quickly.

If you are the steel ball, wouldn't you rather have a large surface area parachute so that you fall slowly?
 
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Are the balls all the same mass?
 
I agree with you. It is difficult to second-guess the book without better context.

Given identical steel balls and different parachutes, the ball/parachute pair with the larger parachute should have the slower terminal velocity.

The ball with the larger parachute will reach (or approach) its terminal velocity in less elapsed time. But the wording of the question seems to make this fact irrelevant.
 
The balls are all the same size and mass. Only the parachute is changed
 
The book author is wrong. If you are ever in a crashing airplane with him and there is only one parachute, you will be a lucky man.
 
I agree. book is wrong. Not the first time.
 
I have fallen at Terminal Velocity many times and I always found that a parachute slowed me down, On the 1 occasion that I used a smaller parachute I believe that I fell faster than with the larger parachute and a lot slower than without the parachute. I would always prefer to hit the ground with an open parachute than without a parachute. Text books do not always have correct answers and/or information. Nothing beats doing your own experiment. (Typos edited)
 
Is this the exact formulation gound in the book? I can also imagine the book asking which of the balls reach terminal velocity more quickly, but this is pure speculation as I do not have the book. See also post #3. If this is not the case, I agree with previous posters.
 
I have re read the question as posted "Question: will the ball with the largest parachute will be traveling more quickly or more slowly than other balls traveling at terminal velocity? " and I realize that I don't understand the question. Perhaps it has not been types correctly.
 
  • #10
The question seems ok to me.

The ball with the largest parachute will be traveling more slowly than other balls (which have a small or no parachute) at terminal velocity.
 

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