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Pet_Sounds · 08-25-2019, 12:22 AM

These are equations for a ball thrown vertically into the air at 5.0 m/s. Position is purple, velocity is green, and acceleration is blue. The x-axis is time. Ignore the bits where the parabola lies below the x-axis; they're not relevant for this example.

The first few Khan Academy videos on physics probably explain this way better than I can.

OccultHawk · 08-25-2019, 12:28 AM

I loved KA when I had a computer but it sucks on a phone.

When I had a computer I had tons of badges and ****.

Then they changed from stars to leaves or something and my computer died.

BassoonPlatoon · 08-25-2019, 01:34 AM

Quote:

Originally Posted by Pet_Sounds

These are equations for a ball thrown vertically into the air at 5.0 m/s.

I did not expect things to launch off like this based on a one sentence blurb of mine that was about 1 minute or 2 of real time. Thanks for taking such an interest, as well as for mentioning Khan Academy it's a useful tool for the individual trying to teach themselves, and their are plenty of ways online to do it in addition.

Anyway, to see if I can add anything here, position of an object is usually always nonzero if you add in the Earth's rotation. I forgot about the forces of gravity when talking about the parked car example so thanks for reminding me about that, kind of a lot more factors of physics to consider than I realized at first, without even mentioning the different subsets.

~~jwb~~ · 08-25-2019, 05:16 AM

Quote:

Originally Posted by Pet_Sounds

No, no matter how small your interval of measure is the ball in midair will always exhibit some movement in that interval.

EDIT: To be clear, we're talking about Newtonian physics here.

what if you're on the moon and you throw the ball

Since gravity is weaker, would the peak last longer?

Pet_Sounds · 08-25-2019, 06:47 AM

Quote:

Originally Posted by BassoonPlatoon

I did not expect things to launch off like this based on a one sentence blurb of mine that was about 1 minute or 2 of real time. Thanks for taking such an interest, as well as for mentioning Khan Academy it's a useful tool for the individual trying to teach themselves, and their are plenty of ways online to do it in addition.

Glad you mentioned it!

Quote:

Originally Posted by BassoonPlatoon

Anyway, to see if I can add anything here, position of an object is usually always nonzero if you add in the Earth's rotation. I forgot about the forces of gravity when talking about the parked car example so thanks for reminding me about that, kind of a lot more factors of physics to consider than I realized at first, without even mentioning the different subsets.

Yeah, reference frame is important.

Quote:

Originally Posted by jwb

what if you're on the moon and you throw the ball

Since gravity is weaker, would the peak last longer?

No, you can't measure the peak as lasting for any length of time in either case.

~~jwb~~ · 08-25-2019, 09:26 AM

I guess that makes sense. So if you graphed the ball being thrown on Earth and the one on the moon, both would just be different shaped parabolas?

OccultHawk · 08-25-2019, 09:44 AM

Quote:

Originally Posted by Pet_Sounds

Glad you mentioned it!

Yeah, reference frame is important.

No, you can't measure the peak as lasting for any length of time in either case.

Can’t? Or is it just not practical for basic physics?

Pet_Sounds · 08-25-2019, 09:55 AM

Quote:

Originally Posted by jwb

I guess that makes sense. So if you graphed the ball being thrown on Earth and the one on the moon, both would just be different shaped parabolas?

Yep! It's just a matter of a different number for the strength of the gravitational field. The parabolic shape of the graph results because acceleration is constant.

https://www.khanacademy.org/science/...nsional-motion

That's a pretty good overview if you want to get a deeper sense of what's going on. (Admittedly I haven't watched it in years, but iirc he does a good job of explaining everything clearly without dumbing it down.) No calculus required.

EDIT:

Quote:

Originally Posted by OccultHawk

Can’t? Or is it just not practical for basic physics?

In terms of the model of Newtonian physics, you can't, as in it's impossible.

OccultHawk · 08-25-2019, 10:20 AM

Quote:

In terms of the model of Newtonian physics, you can't, as in it's impossible.

This has been really interesting and informative. You’re a really smart dude.

grindy · 08-25-2019, 10:54 AM

Pet Sounds really is pretty damn smart but this is all high school level physics.
Are US schools really so ****ty that this is all news for you?

08-25-2019, 12:22 AM	#63951 (permalink)
Pet_Sounds Remember the underscore Join Date: Feb 2014 Location: The other side Posts: 2,488	These are equations for a ball thrown vertically into the air at 5.0 m/s. Position is purple, velocity is green, and acceleration is blue. The x-axis is time. Ignore the bits where the parabola lies below the x-axis; they're not relevant for this example. The first few Khan Academy videos on physics probably explain this way better than I can. Attached Thumbnails __________________ Everybody's dying just to get the disease

08-25-2019, 12:28 AM	#63952 (permalink)
OccultHawk one-balled nipple jockey Join Date: Dec 2010 Location: Dirty Souf Biatch Posts: 22,006	I loved KA when I had a computer but it sucks on a phone. When I had a computer I had tons of badges and ****. Then they changed from stars to leaves or something and my computer died. __________________ 2016 2017 2018 2019 2020 Member of the Year & Journal of the Year Champion Behold the Writing of THE LEGEND: https://www.musicbanter.com/members-...p-lighter.html

08-25-2019, 10:54 AM	#63960 (permalink)
grindy . Join Date: Oct 2014 Location: . Posts: 7,201	Pet Sounds really is pretty damn smart but this is all high school level physics. Are US schools really so **ty that this is all news for you? __________________ A smell of petroleum prevails throughout.**

08-25-2019, 09:26 AM	#63956 (permalink)
~~jwb~~ Account Disabled Join Date: Jul 2019 Posts: 4,403	I guess that makes sense. So if you graphed the ball being thrown on Earth and the one on the moon, both would just be different shaped parabolas?