Concept questions - Laws of Motion

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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

 

[SammyS]

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.

 

[page123]

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?

 

[SammyS]

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 = (F_g)/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?

 

[page123]

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

g = (F_g)/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?

 

[SammyS]

Not because it takes more time per se.

How is force of drag related to speed?