Concept questions - Laws of Motion

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Homework Help Overview

The discussion revolves around Newton's Laws of Motion, specifically exploring interpretations of motion and the effects of mass on falling objects with parachutes. Participants are examining how different thinkers, like Aristotle and Galileo, would interpret the behavior of a ball rolling to a stop and the dynamics of parachuting individuals of varying weights.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to interpret the motion of a ball on a pool table, questioning the role of friction. They are also discussing the implications of mass on parachuting, with conflicting ideas about acceleration and terminal velocity. Questions are raised about the correctness of their reasoning and interpretations.

Discussion Status

Some participants have offered insights into the relationship between mass and terminal velocity, suggesting that a heavier person would reach a higher terminal velocity. There is ongoing exploration of the concepts involved, with no clear consensus yet on the interpretations or conclusions.

Contextual Notes

Participants are navigating through assumptions about gravitational force and drag, with some expressing uncertainty about their interpretations and the implications of their reasoning.

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Homework Statement



Newton's 1st Law of Motion

A ball rolled across the top of a pool table and slowly rolls to a stop. How would Aristotle interpret this behavior? Galileo? You?

Newton's 2nd Law of Motion

If a heavy person and a light person parachute together form the same altitude, and each wears the same size parachute, who should reach the ground first?

Homework Equations



* Fnet = m * a

* Faction = -Freaction

The Attempt at a Solution

 
Last edited:
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What are your answers?

What have you tried? Where are you stuck?

I see that you have 28 posts on this site. You should know the drill by now.
 
SammyS said:
What are your answers?

What have you tried? Where are you stuck?

I see that you have 28 posts on this site. You should know the drill by now.

I edited out the ones I'm not stuck on, I'm not sure how I would interpret the ball rolling and stopping on the table (friction?) and about the heavy/light person parachute thing I'm getting two answers:

1) g = Fg/m, right? so they would be similar ratios but one has a higher mass and bigger Fg, but they would both reach at the same acceleration --> same time reach the ground

2) the lighter person reaches terminal velocity first but the heavier person keeps accelerating (not sure how) so the heavier person hits ground first

which is right?
 
page123 said:
I edited out the ones I'm not stuck on, I'm not sure how I would interpret the ball rolling and stopping on the table (friction?) and about the heavy/light person parachute thing I'm getting two answers:

1) g = Fg/m, right? so they would be similar ratios but one has a higher mass and bigger Fg, but they would both reach at the same acceleration --> same time reach the ground

2) the lighter person reaches terminal velocity first but the heavier person keeps accelerating (not sure how) so the heavier person hits ground first

which is right?
"g = Fg/m, right?" Wow, that's hard to read. Looks like g should cancel. --- But I presume you mean that:

g = (Fg)/m .

Your answer #2 is the better of the two. Actually another factor is that terminal velocity is greater for the heavier person. Can you explain why that is true?
 
SammyS said:
"g = Fg/m, right?" Wow, that's hard to read. Looks like g should cancel. --- But I presume you mean that:

g = (Fg)/m .

Your answer #2 is the better of the two. Actually another factor is that terminal velocity is greater for the heavier person. Can you explain why that is true?

Is it because terminal velocity is defined as when the force of gravity is balanced by the force of drag? So since a heavier person has a heavier weight, the terminal velocity will be greater because it takes more time to balance out the weight while accelerating?
 
Not because it takes more time per se.

How is force of drag related to speed?
 

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